MISCELLANEOUS PROCESSES.
The various processes and details which have occupied the preceding
chapters, are for the most part necessary to the production of every
house. There are, however, many articles of iron and a few of brass
employed in the interior and exterior fittings; but were we to enter
into details respecting the iron manufacture, in order to show the
modes of producing these articles, it would be difficult to confine
this volume within reasonable limits. A few miscellaneous processes and
details may, however, be collected in this chapter.
The principal metallic articles employed in the construction or
permanent fittings of a house, are nails and screws; hinges; locks and
keys; stoves and grates; bells, and the mechanism for hanging them;
iron railings and bars; brass handles, plates, and other decorations;
latches and fastenings, &c.
Nails.
_Nails_ are made of iron, either _cut_ by means of a machine into the
tapering form which we call _cut brads_, or _wrought_ by means of
hammers into the various forms of flooring nails, tacks, &c. _Screws_
are made by forcing a piece of iron wire into a cavity, the surface
of which is cut into a spiral or screw-like form; this spiral cuts a
similar spiral on the surface of the iron wire, which then becomes a
screw; and one end of the wire is hammered or pressed down so as to
form the _head_ of the screw. _Hinges_ of the commoner kinds are made
by two flat pieces of iron, with a kind of projecting tube at one edge.
These tubes are partially cut away, so that the two pieces may lap into
each other; and a spindle or pin being passed down through both tubes,
acts as an axis, on which both parts of the hinges turn. The more
costly hinges require elaborate workmanship in their construction.
Locks and Keys.
_Locks_ and _Keys_ form a curious part of the hardware manufacture.
The lock is made of a great many pieces, put together with screws.
One part of it is always a moveable latch or bolt, which is capable,
by tolerable force, of being thrust partially out through a hole in
the side of the lock; and it is this bolt which, catching in a box or
cell fixed to the door-post, secures the door to which the lock is
attached. The object of the key is to act as a lever which shall move
the bolt; and the great point of attention in the matter is, that no
key or lever but one of a particular _size_ and _shape_ shall be able
to move the bolt; herein is the security which we feel in a good lock.
Wolverhampton and its neighbourhood is the great seat of the lock
manufacture.
Stoves and Grates.
_Stoves_ and _Grates_ are made in a variety of forms. Their employment
is obviously greatly dependent on the kind of fuel employed. In the
kitchens of the old baronial residences, large logs of wood were
thrown upon an immense stone or brick hearth, and there kindled. But
when coals became commonly used in London and other great towns of
England, about the year 1400, the use of some kind of stove or grate
began to be felt, since the fuel was too valuable to be scattered
on a wide-spreading hearth. From that time to the present, one
continual series of improvements has taken place, having for their
objects, to add to the elegance and neatness of a room, to facilitate
culinary occupations, and to derive the greatest possible heat from
a given quantity of fuel. It is only within a very few years that
the principles regulating the last-mentioned circumstance have been
at all well understood. Some parts of the metal for a grate or stove
are produced by casting, others by forging, and others by rolling or
pressing; and they are put together principally by rivets. For further
details on this subject we refer to our seventh chapter.
Bells.
_Bells_ are, generally speaking, made of an alloy of copper and tin,
which possesses more resonant qualities than most others. There is also
a little ball or clapper suspended in the bell, which, by striking
against it, produces the same effect as the hammer which strikes the
outside of a church bell. The bell is generally fixed in a different
part of the house from the handle with which it is rung, and the
connexion between them is made by means of copper wire. As the wire has
to turn round many corners and angles, it is fixed, at each corner to a
_crank_, which is a kind of hinge or lever, so contrived as to transfer
motion in a new direction at right angles to the former. Considerable
care is required on the part of the bell-hanger, to prevent the wire
from becoming entangled or interrupted in its free communication from
the handle to the bell.
Brass Handles, Ornaments, &c.
Those are produced by _turning_, by _casting_, by _stamping_, or by
_drawing_. In the first mode, the article is placed in a lathe, and
turned by tools made of hard steel: in the second mode, melted brass
is poured into moulds formed generally of sand, by which any desired
form is produced: in the third mode, two stamps, one called a _matrass_
and the other a _die_, are cut or moulded to similar figures; a piece
of sheet brass is laid on the matrass or lower stamp, the die or upper
stamp is laid on the brass, and a powerful blow, either from a hammer,
or from machinery, forces the brass to assume the form given to the
two stamps. By the last mode, a slip of thin brass is forcibly drawn
between two rollers, whose surfaces are indented with the requisite
device, which device is thereby impressed on the bars. In one or other
of these ways, most of the brass-work in our houses is made.
_Iron railings_ and _bars_ of various kinds are made either by forging
or casting, and do not call for further notice here.
Preservation of Timber.
In our notices of the timber which enters into the construction of a
house, no mention was made of the existing methods of preparing it so
as to resist the action of dry rot and other decomposing agencies.
Timber so prepared is not in very general use in house-building, and
hence the notice of it occupies a more fitting place in the present
chapter.
Vegetable matter, in common with all organic substances, is subject
to decomposition and decay, as soon as life becomes extinct; and
although the process is comparatively slower in its commencement
and progress in vegetable than in animal matter, it is not, under
ordinary circumstances, the less certain. During the existence of
a plant, its various organs, under the influence of the mysterious
principle of life, perform their respective functions in a manner
similar to that of which we are more readily conscious in the animal
frame. The plant absorbs its food from the soil and the surrounding
air; it digests that food under the influence of respiration, and
prepares rich and nutritive juices which circulate throughout its whole
vegetable frame, and deposit materials of growth wherever they are
wanted; it sheds its leaves in autumn, undergoes a season of torpor,
and again becomes active and vigorous; thus it is clad in fresh leafy
honours in the following spring. All this is the effect, or rather the
result, of vitality. The plant dies, and then its constituent parts
gradually assert their individual existence, and resume their original
affinities. Some pass into the air; some form new compounds; and
others, which during the life of the plant ministered to its healthy
action, now work energetically and destructively on each other; so
that the original mass gradually decomposes under the influence of
various causes. The first step to decay is a process of fermentation,
which is more or less rapid in proportion as heat and moisture are
more or less present. In the absence of damp air, even the vegetable
mass will of itself supply moisture; for, according to Count Rumford,
the best-seasoned timber retains one-fourth of its weight of water. A
certain extent of moisture is essential to vegetable fermentation; but
a complete saturation appears inimical to it. A temperature not so low
as to produce freezing, nor so high as to produce rapid evaporation, is
also favourable to it. The humidity of the air in ships, and in houses
built on clay or in moist situations, and the difficulty of obtaining
a free circulation of air, contribute greatly to this fermentative
process.
The chemical constitution of the vegetable kingdom yields to analysis
only three or four ultimate elements, viz., oxygen, hydrogen, and
carbon, and sometimes nitrogen. The most active agent in the process
of decomposition is the oxygen contained in the dead plant, whether
such decomposition proceed under the rapid influence of fermentation,
or be produced more slowly by the operation of the law which renders
decay the necessary consequence of organization. As soon as the tree
is felled, the oxygen begins to be liberated and to act upon the woody
fibre, combining with its carbon, and producing carbonic acid gas. The
tenacity of the several parts is thus gradually destroyed. After timber
is felled, and during the process of seasoning, a gradual diminution
of strength may be remarked. The effect, however, of seasoning is to
deprive the wood of superabundant moisture, and of those vegetable
juices which would otherwise induce a rapid decomposition.
In addition to the natural decay of timber, the decomposition is often
accompanied by the apparently spontaneous vegetation of parasitical
fungi, inducing a species of decay to which the term “dry rot” is
applied, probably in consequence of the attendant phenomena; the
wood being converted into a _dry_ friable mass, destitute of fibrous
tenacity. It is uncertain whether the seeds of these fungi exist in
a dormant state in the juices of the timber, and wait only until the
first stages of decomposition furnish them with a nidus favourable to
their growth; or whether they float in the atmosphere and settle in
places favourable to their vegetation. It is found, however, that
badly-seasoned timber is peculiarly subject to this species of decay;
and hereby the former of the two suppositions is favoured.
From the moment when timber is felled, the process of decay commences,
and although so slowly in many cases that we are not conscious of it,
yet there is a limit to the existence of the most durable articles
of wood, however carefully preserved. Dryness, cleanliness, a free
circulation of air, or the entire exclusion of it, are among the best
checks to vegetable decomposition: while damp accumulations, and a
vitiated atmosphere, rapidly induce it.
Unseasoned timber should never be used in carpentry, and the
best-seasoned timber should be used only in a dry state. Diseased and
decayed portions of the wood should be cut out, together with the
sap-wood, which, being more soft and porous than the spine, is more
liable to fermentation.
The iron fastenings used about timber frequently cause its premature
decay. Iron, under the influence of moisture becomes rusty, that is,
oxygen, either from the air or from the wood itself, unites with the
metal, forming an oxide, which, in its turn acts upon the woody fibre,
and gradually destroys its tenacity. The iron is further subject to
attack from the acid juices of the wood; this effect, however, varies
in different woods. Oak contains a smaller proportion of oily or
resinous particles than many other kinds of wood; and, in addition to
the usual vegetable acid common to most woods, oak contains an acid
peculiar to itself, called _gallic_ acid. In teak, on the contrary,
the quantity of acid is not only smaller, but the resinous particles
are very abundant, and these form a sort of protecting covering to
the iron fastenings. Maconochie states, on the authority of the
shipping built in India and used in the India trade, that the average
duration of an iron-fastened teak ship is thirty years; and that it
is a misapplication of expense to use copper fastenings with teak, as
the additional advantage gained is not at all commensurate with the
additional expense. But it is different with oak; the action of oak on
copper is by no means so destructive as on iron, and the reaction of
the metal on the wood is not so destructive.
The methods which have been from time to time adopted for the
preservation of timber are so numerous, that a slight sketch of them
would probably fill a good-sized volume. We will name a few of the most
successful, and terminate this notice with a description of the method
now in practice.
Maconochie recommends all the iron fastenings to be provided with
a protecting paint, and to impregnate the timber with some oily
preparation, which he proposes to effect thus: the wood is to be
placed in a steam-tight chamber, and subjected to the action of steam,
by which the air will be expelled from the timber. Then by condensing
the steam, and repeating the process until all the elastic fluids are
withdrawn from the wood, and its juices converted into vapour, the
wood becomes freed from them, and if plunged into oil, and subjected
to atmospheric pressure, all the internal cavities of the wood will
be filled with oil. In this way, Maconochie had in daily use a
steam-chamber capable of containing twenty or thirty planks of timber
forty feet long, in which, while the planks were steaming, to render
them flexible, they were impregnated with teak oil. He says the oil may
easily be procured from the chips and saw-dust used for the fuel of the
steam-boilers; for it has been ascertained that Malabar teak contains
such a quantity of oleaginous (oily) or terebinthinous (turpentine)
matter, that the chips from the timber and planks of a ship built of
it will yield, by a proper process, a sufficient quantity of tar for
all its own purposes, including the rigging; and that, although oak
timber does not contain so much of these substances, the chips of the
fir alone consumed in the Royal Navy, would be more than sufficient to
supply tar to saturate the oak.
There have been many other proposals to saturate timber with different
substances; the most successful of which, up to the process of Mr.
Kyan, was that of M. Pallas, whose plan was to saturate the timber in
a solution of sulphate of iron, and then precipitate the salt by means
of lime-water. About the year 1822, Mr. Bill produced samples of timber
impregnated throughout with a substance resembling asphaltum. These
samples were subjected to a trial of five years in the dry-rot pit
at Woolwich, and withstood the fungus-rot perfectly. Sir John Barrow
recommends kreosote, which he says, “in a vaporous form, penetrates
every part of the largest logs, and renders the wood almost as hard as
iron--so hard as not easily to be worked.”
Mr. Kyan’s plan, now so universally adopted, is to soak the timber in a
solution of bichloride of mercury, commonly called corrosive sublimate.
“Aware of the established affinity of corrosive sublimate for albumen,
Mr. Kyan applied that substance to solutions of vegetable matter, both
acetous and saccharine, on which he was then operating, and in which
albumen was a constituent, with a view to preserve them in a quiescent
and incorruptible state; and obtaining a confirmation of his opinions
by the fact, that during a period of three years, the acetous solution,
openly exposed to atmospheric air, had not become putrid, nor had
the saccharine decoction yielded to the vinous or acetous stages of
fermentation, but were in a high state of preservation, he concluded
that corrosive sublimate, by combination with albumen, was a protection
against the natural changes of vegetable matter. He conceived,
therefore, if albumen made a part of wood, the latter would be
protected by converting that albumen into a compound of protochloride
of mercury and albumen; and he proceeded to immerse pieces of wood
in this solution, and obtained the same result as that which he had
ascertained with regard to the vegetable decoctions.”--BIRKBECK.
It having been found that the precipitate caused by the Kyanization
was soluble in salt water, Sir William Burnett has lately substituted
chloride of zinc for corrosive sublimate, and the resulting compound
which this forms with the albuminous portion of the wood, effectually
resists the action of salt water.
Soluble Glass.
A remarkable method of preserving wood-work, and rendering it
fire-proof, was invented some years ago by M. Fuchs, in consequence of
his discovery of a kind of glass which could be prepared and kept in a
liquid state, and hardened only on being exposed in a thin layer to the
air.
Soluble glass is a union of silica and an alkali, which has, in
addition to some of the properties of common glass, the property of
dissolving in boiling water. The preparation of soluble glass does
not greatly differ in its early stages from that of common glass, an
account of the manufacture of which will be found in the eighth chapter.
When sand and carbonate of potash are heated together, the carbonic
acid is not entirely driven off, unless the sand be in excess, but the
whole of the gas may be expelled by the addition of powdered charcoal
to the mixture.
Carbonate of potash and pure sand being taken in the proportion of
two to three, four parts of charcoal are added to every ten parts of
potash and fifteen of sand. The charcoal accelerates the fusion of the
glass, and separates from it all the carbonic acid, a small quantity of
which would otherwise remain, and exert an injurious effect. In other
respects the same precautions that are employed in the manufacture
of common glass are to be observed. The materials must first be well
mixed, then fritted, and finally melted at a high heat, until a liquid
and homogeneous mass be obtained. This is removed by means of an iron
ladle, and the glass pot filled with fresh frit.
The crude glass thus obtained is usually full of bubbles: it is as
hard as common glass: it is of a blackish gray, and more or less
transparent at the edges. Sometimes it has a whitish colour, and at
others is yellowish or reddish, indicating thereby that the quantity
of charcoal has been too small. Exposed to the air for several weeks,
it undergoes slight changes, which tend rather to improve than injure
its qualities. It attracts a little moisture from the air, which slowly
penetrates its mass without changing its aggregation or appearance,
except that it cracks, and a slight efflorescence appears at its
surface. If after this it be exposed to heat, it swells up, owing to
the escape of the moisture it has absorbed.
In order to prepare the glass for solution in water it must be reduced
to powder by stampers. One part of the glass requires from four to five
of water for its solution. The water is first boiled in an open vessel,
the powdered glass is added gradually, and is continually stirred, to
prevent its adhesion to the vessel. The boiling must be continued for
three or four hours, until no more glass is dissolved. If the boiling
be checked before the liquor has thus attained the proper degree of
concentration, carbonic acid will be absorbed by the potash from the
air, and produce an injurious effect. When the solution has acquired
the consistence of syrup, and a density of 1·24, it is fit for use.
It is then allowed to repose, in order that the insoluble parts may
be deposited: while it is cooling a film forms on the surface, which
after some time disappears, or may be dissolved by depressing it in the
liquor.
Soluble glass being employed only in the liquid state, it is preserved
for use in solution. No particular care is necessary to preserve
the liquid, as, even after a long space of time, it undergoes no
perceptible change, if the solution have been properly prepared. The
only precaution is not to allow too free an access of air to it.
Soluble glass may be prepared by using carbonate of soda, instead of
that of potash. This glass has the same properties as the other, but is
more valuable in its applications. The solutions of these two kinds of
glass may be mixed in any proportion, and the mixture is sometimes more
useful than either of the solutions separately.
The solution of soluble glass is viscid, and when concentrated
becomes turbid or opalescent. The solution unites with water in all
proportions. At a density of 1·28 it contains nearly 28 per cent.
of glass, and if the concentration be carried beyond this point, it
becomes so viscid that it may be drawn out in threads like molten
glass. When the solution is applied to other bodies, it dries rapidly
in the air, and forms a coat like a varnish; a property which leads us
to notice some of the numerous and varied applications of this curious
preparation.
It is well known that all sorts of vegetable matter, such as wood,
cotton, hemp, linen, paper, &c., are combustible, but in order to burn
them, two conditions are necessary,--an elevated temperature, and
free access of air to supply the oxygen necessary to their conversion
into water and carbonic acid. When once inflamed their own combustion
supplies the heat necessary to the chemical action, provided they be in
contact with the air. If deprived of such contact, and made red-hot,
they will yield inflammable volatile products, but the residual carbon
will not burn, because deprived of air; and thus the combustion will
cease of itself. Such is the property of all the fixed fusible salts,
if they be composed of substances incapable of yielding their oxygen
at a low red heat, either to carbon or hydrogen. Such salts melt as
the vegetable matter becomes healed: they form upon it a coating
impermeable by air, and either prevent or limit the combustion. The
phosphate and borate of ammonia have such a character, but they are so
readily soluble in cold water as to be liable to objections which are
not found in soluble glass. This last-named substance forms a solid
and durable coating, which suffers no change by exposure to the air
(since soluble glass possesses the valuable properly of being almost
entirely unaffected by cold water): it does not involve any great
expense, and is easy of application. But in order that it may not fail,
particular care must be taken, both in preparing and employing it. To
cover wood and other bodies with it the solution must be made of a
pure glass, otherwise it would effloresce and fall off. But still a
slight degree of impurity is not injurious, although after a few days a
slight efflorescence will appear: this may be washed off by water, and
will not occur a second time. When a durable coating is to be applied
to wood, the first solution must not be too strong, for if it be it
will not be absorbed: it will not displace the air from the pores, and
consequently will not adhere strongly. A more concentrated solution
may be employed for the after-coats, but each coat must be dry before
another is applied, and the drying, in the most favourable weather,
will occupy at least twenty-four hours. When the glass is made with
potash the coating is liable to crack: this defect does not apply to
glass made with soda.
Although soluble glass is of itself a good preservative from fire, yet
it fulfils the object better when mixed with incombustible powders,
such as those procured from clay, whiting, calcined bones, powdered
glass, &c. In applying soluble glass to the wood-work of a public
building at Munich, ten per cent. of yellow clay or yellow earth was
added. After six months the coating had suffered but little change: it
was damaged only in a few places, where it had need of some repair.
This arose from the very short time allowed for the preparation and
application of the glass.
On Veneering.
In our notice of the interior fittings of houses of the better class,
it was stated that the process of veneering is sometimes adopted for
wainscoting. This process is most generally used for articles of
furniture, and deserves to be noticed on account of its ingenuity.
The employment of wood for articles of domestic use or ornament, gives
rise to many departments of mechanical labour, according to the manner
in which the grain of the wood is to be made conspicuous or visible.
In the antique pieces of furniture still existing in old mansions,
the wood employed, such as oak, walnut-wood, mahogany, &c., was
always solid; but in modern times, the desire of making a respectable
appearance, at as small an outlay as possible, has led to the method of
_veneering_,--that is, making some article of furniture of some cheap
wood,--such as deal,--and then covering it with thin leaves or sheets
of some more expensive and beautiful wood, such as rose-wood, maple,
satin-wood, zebra-wood, pollard oak, &c. So very prevalent has this
custom become, that almost every house now contains some article of
domestic furniture, whose surface is covered with a kind of wood more
valuable than that of which the bulk of the article is made.
It must be obvious, that the mode of procuring or preparing the thin
leaves of veneer calls for great care and nicety, since they are
seldom thicker than a shilling. When the method of veneering was first
introduced, the sawing was effected by hand, in a manner more rude than
the necessities of the case warranted; but when circular saws became
introduced, they were found very efficacious for cutting veneers. Mr.
Brunel, in 1805, took out a patent for improvements in the machinery
for sawing timber, in which he employed a large circular saw, composed
of several pieces fitted together, and placed in a frame at such an
elevation that the lower edge was a little below the lower side of the
timber. The timber was placed in a carriage, and moved towards the saw
by a rack.
In such a manner as this veneers are now cut from the timber in this
country. But it is stated that the Russians have devised a very
curious and effective method of cutting veneers, without the use of
a saw, and without making any waste of material. It is a _planing_
machine, the action of which is so accurate, that veneers thin enough
for the covering of books, and for lithographic and other engravings,
have been produced; thus serving the place of paper. The operation
is begun by placing the timber from which the leaf is to be cut upon
a square axle, where it is revolved, and made circular by a turner’s
gouge. The blade of a plane of highly-tempered steel, and rather
longer than the cylinder of wood, is fixed at the extremity of a frame
six or seven feet in length, in such a manner as to exert a constant
pressure upon the cylinder, and pare off a sheet of equable thickness,
which folds upon another cylinder like a roll of linen. The frame
to which the blade is attached is moveable at its lower extremity,
and by the action of a weight it depresses in proportion as the mass
diminishes in substance. That this depression may be progressive and
perfectly regular, the inventor has appended a regulator to the machine
consisting of a flat brass plate, preserved in an inclined direction,
upon which the frame descends as the regulator itself is advanced. The
motion is communicated to the cylinder of wood by several cog-wheels,
which are turned by a crank. One hundred feet in length of veneering
may be cut by this machine in the space of three minutes.
When veneers are produced by the action of circular saws, as is now
almost universally the case in England, it is evident that both
surfaces must be rough, from the marks of the serrated edge of the
cutting instrument; and it is in this rough state that they are
purchased by cabinet-makers or others who employ them in veneering
articles of furniture. The operations which are then to be performed
are, to bring the surface of the veneer to a tolerable level, to fix
the veneer to the article of furniture, and to clean and polish it when
so fixed.
Supposing the top of a sideboard to be the article which is to be
veneered. The workman cuts out a piece of veneer, a little larger than
is actually required, to allow for waste; and then lays it flat on
his work-bench. With a veneering plane--which is a small-sized plane,
having an iron jagged with notches like the teeth of a very fine
saw--he works steadily over the whole surface of the veneer, carrying
the plane in the direction of the grain of the wood. The action of this
plane-iron removes all the saw marks, which were irregular in their
course, and gives instead of them a series of regular parallel channels
from end to end of the piece of veneer; these channels are but small in
depth, and their object is to retain the glue which is afterwards used
in the process of veneering.
The surface of the deal or other wood on which the veneer is to be
laid, is in like manner planed with these parallel indentations; and
then the process of veneering proceeds. The wood, having been well
warmed before a fire, is coated with warm melted glue; and the piece of
veneer is laid down flat on the veneered surface, and rubbed backwards
and forwards, in order that the glue which is between the veneer and
the under-wood may be pressed into all the little grooves produced by
the plane. When the glue begins to get cool, the veneer can no longer
be pressed to and fro, and is then left. This glueing has the general
effect of making the veneer adhere to the foundation beneath; but there
are parts where, from the accumulation of too much glue in one part, or
from the presence of air which had not been expelled by the pressure
of the hands, the veneer rises up as a kind of blister, convex on the
upper surface. The workman employs a veneering hammer to level these
protuberances. This veneering hammer is a piece of wood three or four
inches long, and an inch in thickness, having a straight strip of iron
plate fixed to one edge. The workman, placing the iron edge down upon
the veneer, presses on the block of wood with his hand, and works all
over the surface of the veneer, expressing all the superfluous glue
from the parts which had formed the protuberances. As this redundant
glue must have some place from whence to escape, the workman begins
rubbing at the centre, and thence proceeds towards the edge, at
which the glue finally exudes. There is a curious plan adopted for
ascertaining whether there are any parts, imperceptible to the eye,
where the veneer does not adhere closely to the foundation--viz., by
sound. The workman strikes the veneer all over with a wooden or other
hammer; and if the sound be distinct and solid, he knows that the
proper degree of adhesion has taken place; but if the sound be hollow
and dull, it indicates the existence of a vacant space between the
veneer and the foundation; and a greater degree of rubbing or pressing
is consequently necessary. If the surface of the piece of veneer be of
large dimensions, two workmen are required to level all parts of the
veneer before the glue gets cold and loses its fluidity.
But this operation--however good the glue may be, or however well the
veneer may be pressed down--is not sufficient to cause the veneer to
adhere permanently to the foundation, especially at the edges, where
the air is liable to enter, and to cause the veneer to rise. To prevent
this inconvenience, the veneer, at and near the edges, is kept down,
either by the pressure of heavy weights, or, still better, by the
action of screw-presses. These screw-presses consist of two pieces
of wood or clamps, which are brought to any degree of closeness by
means of two wooden screws, each screw passing through holes in both
clamps, the handles of the two screws being, respectively to each
other, outside the opposite clamps. The clamps are opened, by means of
the screws, to such a width as to admit the edge of the veneered wood
between them; and the screws are then worked up till the clamps grasp
the wood tightly, where they remain till the glue is quite cold, and
the veneer closely adhering to the foundation.
But even all this care is not in every case sufficient to produce a
firm adhesion of the veneer to the foundation. It frequently happens
that, when the hardened veneered surface is tried with the hammer, a
hollow sound indicates that there is yet a place where the veneer has a
vacancy beneath it. In such a case, the only remedy is one of a curious
kind--viz., to lay a hot iron on the defective part of the veneer,
by which the glue beneath is remelted. A small part of the veneer,
reaching from the defective part to the edge, is also similarly heated,
and the glue beneath remelted. Then, by means of the veneering hammer,
the superfluous glue which had caused the defect is squeezed out, and
pressed to the edges of the veneer through the kind of channel which
had been prepared for it by the heated iron.
Where the surface of the wood to be veneered is more or less
cylindrical, such as a pillar, the front of a drawer, &c., the piece
of veneer has a curvature given to it, corresponding in some degree to
that of the surface on which it is laid, by the action of hot water,
before the glueing is effected. By sponging one side of the veneer with
hot water, it causes that side to swell, while the other side remains
dry; the consequence of which is, that the wetted surface rises into
a convex form, leaving the other side hollow or concave:--this is, in
fact, an instance of _warping_, where a thin piece of wood is either
unequally heated or damped on opposite sides. The hollow side is then
laid on the glued foundation.
When the veneered surface is dry, its edges are trimmed, and its
surface scraped and sand-papered, preparatory to the finishing
processes which the piece of furniture is to undergo.
Manufacture of Glue.
The preparation of this useful article forms a curious and important
branch of national industry. The chief use of glue is for binding or
cementing pieces of wood together, as practised by the carpenter and
cabinet-maker, in which trades very large quantities are constantly
employed.
Glue (which is nothing more than gelatine in a dry state) is obtained
from the hides, hoofs, and horns of animals; the refuse of the
leather-dresser, and the offal of the slaughter-house; ears of oxen,
calves, sheep; parings of parchment, old gloves; and, in short, animal
skin and (by a late improvement) bones, are all employed for making
glue.
The first process in this manufacture is to free the materials from
dirt, blood, and other matters which do not afford glue. For this
purpose they are steeped in lime and water, and then placed in baskets,
and rinsed by the action of a stream of water. They are then removed to
a sloping surface, and allowed to drain, and whatever lime remains is
deprived of its caustic property by the reabsorption of carbonic acid
from the atmosphere, since the presence of lime would prove injurious
in the subsequent processes.
The gelatine is removed from the animal matter by boiling. This
process is effected in a somewhat shallow boiler, which is provided
with a false bottom, pierced with holes, and elevated a few inches,
thus serving as a support to the animal matter, and preventing it
from burning by the heated bottom of the boiler. The boiler is filled
about two-thirds with soft water, and then the animal substances are
added: these are piled up above the brim of the boiler, because soon
after boiling commences, they sink down below the level of the liquid.
The contents of the boiler are occasionally stirred up and pressed
down, while a steady boiling is maintained throughout this part of the
process.
As the boiling proceeds, small portions of the gelatine are drawn off
into egg-shells, when, in the course of a few minutes, if the liquid
gelatine becomes, by exposure to the cool air, a clear mass of jelly,
the boiling process is complete,--the fire is smothered up, and the
contents of the boiler left to settle for ten or twenty minutes. The
stop-cock is then turned, and the gelatine flows into a deep vessel,
kept hot by being surrounded with hot water, and thus it remains for
several hours, during which time it deposits any solid impurities. It
is then drawn off into congealing boxes, and prepared as we shall soon
explain.
The undissolved matter in the boiler is treated with boiling water a
second, and even a third time, and the above process continued until
nothing more can be extracted. The subsequent solutions are often too
weak to be made into glue, but they are economically used with fresh
portions of animal matter.
A clear idea may be formed of this part of the manufacture by the
annexed illustration, which represents a section of three vessels, on
different levels. The uppermost vessel, which is heated by the waste
heat of the chimney, supplies warm water to the animal matter contained
in the second vessel: the third vessel receives the liquid gelatine,
and retains it in a fluid state, while the solid impurities are being
deposited.
[Illustration]
The gelatine is drawn off from this third vessel into buckets, and
conveyed to the congealing boxes. These boxes are of deal, of a square
form, but somewhat narrower at bottom than at top. The liquid glue is
poured through funnels, provided with filter-cloths, into the boxes
until they are entirely filled. This process is conducted in a very
cool and dry apartment, paved with stone and kept very clean, so that
any glue which may be spilt may be recovered. In twelve or eighteen
hours the liquid glue becomes sufficiently firm for the next process,
which is performed in an upper story, furnished with ventilating
windows, so as to admit air on all sides. The boxes are inverted on a
moistened table, so that the cake of jelly may not adhere to it: this
cake is cut into horizontal layers, by means of a brass wire, stretched
in a frame, and is guided by rulers, so disposed as to regulate the
thickness of the cake of glue. The slices thus formed are carefully
lifted off, and placed on nets stretched in wooden frames. As these
frames are filled they are placed over each other, with an interval of
about three inches between every two frames, so that the air may have
free access. Each frame is so arranged as to slide in and out like a
drawer, to allow the cakes to be turned, which is done two or three
times every day.
An experienced writer on manufactures thus observes, concerning this
part of the process:--“The drying of the glue is the most precarious
part of the manufacture. The least disturbance of the weather may
injure the glue during the two or three first days of its exposure.
Should the temperature of the air rise considerably, the gelatine
may turn so soft as to become unshapely, and even to run through the
meshes upon the pieces below, or it may get attached to the strings
and surround them, so as not to be separable without plunging the
net into boiling water. If frost supervene, the water may freeze,
and form numerous cracks in the cakes. Such pieces must immediately
be remelted and reformed. A slight fog even produces upon glue newly
exposed a serious deterioration, the damp condensed upon its surface
occasioning a general mouldiness. A thunder-storm sometimes destroys
the coagulating power in the whole laminæ at once, or causes the glue
to _turn_ on the nets, in the language of the manufacturer. A wind too
dry or too hot may cause it to dry so quickly as to prevent it from
contracting to its proper size, without numerous cracks and fissures.
In this predicament the closing of all the flaps of the windows is
the only means of abating the mischief. On these accounts it is of
importance to select the most temperate season of the year, such as
spring and autumn, for the glue manufacture.”
When the glue is properly dried a gloss is imparted to each cake, by
dipping it in hot water, and passing over it a brush, also wetted
with hot water. The cakes are then placed on a hurdle, dried in the
stove-room, or in the open air, if the weather be sufficiently dry and
warm. It is then packed in casks for sale.
It has been found by experiment that when two cylinders of dry ash, one
inch and a half in diameter, were glued together, and after twenty-four
hours torn asunder, a force of 1260 pounds was required to produce the
separation, thus making the force of adhesion equal to 715 pounds per
square inch. Another experiment made the force of adhesion to equal
4000 pounds on the square inch.
The House-Decorator of Italy.
In an interesting notice, by Mr. Wilson, of the present state of
the arts in Italy, read before the Society of Arts, in Scotland,
in November, 1840, a few details are given of the skill with which
the house-builder converts the commonest materials into tasteful
decorations. The following is an abstract of that part of the notice
which relates to the subject of the present volume:--
Notwithstanding the comparatively small employment afforded to Italian
architects in the present day, yet there can be no question as to the
skill displayed in erecting their designs. The masonry is excellent,
and the ancient Roman brick-work is rivalled by that of the present
generation; houses are built of brick, in which all the exterior
decorations are moulded in that material as perfectly as if executed in
stone. The skill with which the Italian workmen build in brick, may be
exemplified by the Florentine practice of arching over rooms without
centering of any description. Two thin moulds of board, the shape of
the intended arch, alone are used: these are placed at each end of the
apartment which it is intended to cover in, and pieces of string are
stretched from the one to the other, guiding the workman as he advances
in the formation of his arch, which he builds, uniting the bricks by
their thin edges (greatly thinner than those we use), and trusting
entirely to the tenacity and quick-setting of the cement.
Plastering is also carried to a perfection in Italy, of which we have
very little idea in this country; rooms are so exquisitely finished,
that no additional work in the shape of house-painting is required; but
the polish of the plaster, and its evenness of tint, are such as to
rival those of the finest porcelain. Sometimes the plaster is fluted,
or various designs are executed in _intaglio_ upon it, in the most
beautiful manner. Scagliola, a very fine preparation from gypsum, is
the material chiefly used. An instance of the cheap rate at which this
work is done, is afforded in the new ball-room in the Palazzo Pitti
grand-ducal residence at Florence, which, including mouldings, figures,
bas-reliefs, and ornaments, was executed at a cost of two crowns for
every four square feet.
A most beautiful art among the Italians, and one which might be
advantageously introduced into this country, is that of making what are
termed Venetian pavements. This method of finishing the floors of rooms
is conducted in the following manner. In the first place a foundation
is made of lime mixed with pozzolana, and small pieces of broken stone;
this is, in fact, a sort of concrete, which must be well beaten and
levelled. When this is perfectly dry, a fine paste, as it is termed
by the Italians, must be made of lime, pozzolana, and sand; a yellow
sand is used which tinges the mixture; this is carefully spread to a
depth of one or two inches, according to circumstances. Over this is
laid a layer of irregularly broken minute pieces of marble of different
colours, and if it is wished these can be arranged in patterns. After
the paste is completely covered with pieces of marble, men proceed to
beat the floor with large and heavy tools made for the purpose; when
the whole has been beaten into a compact mass, and the paste appears
above the pieces of marble, it is left to harden. It is then rubbed
smooth with fine-grained stones, and is finally brought to a high
polish with emery powder, marble dust, and lastly, with boiled oil
rubbed on with flannel. This makes a durable and very beautiful floor,
which in this country would be well adapted for halls, conservatories,
and other buildings.
The carpentry of the Italians, as observable in ordinary houses,
displays little skill and indifferent workmanship, but in the roofs
and floors of important buildings, they satisfactorily prove their
knowledge of scientific principles, and several of their designs are
well known to British architects.
With regard to the working of iron, in comparison with our system, the
Italian is primitive indeed; yet at times he can and does produce very
good specimens of workmanship, but at a heavy cost; consequently they
are generally content with very ordinary productions. A manufactory
of wire, and of driving and screw nails, by means of machinery, now
occupies the villa of Mecænas at Tivoli; the articles produced are
very well made. Copper is extensively used in Italy, and there are
productive mines in the _Maremma Toscana_. The workmanship of articles
made of this metal is respectable; various utensils are made of brass
in a neat and satisfactory manner, but in the interior finishing of
houses, if much nicety is required, articles of foreign manufacture are
used.
House-painters may be mentioned in the last place, and these display
much taste and skill; and there is a class of them who greatly excel
those in this country, having more the feeling and taste of artists.
Surrounded by the finest models in this art, the Italian decorator
enjoys every advantage in its study, and he inherits besides from the
best periods of art, or rather from antiquity, taste, and a good system
of workmanship. He is not a mere machine, employed in the use of the
moulds, stamps, and other mechanical contrivances, which too often keep
the decorative arts within such narrow limits.
Fresco Painting.
The proposed introduction of Fresco Painting into our public buildings
will, it is hoped and expected, have the effect of employing the artist
in fresco upon the walls of our dwelling-houses. Already have a few of
the mansions of our nobility been thus decorated, and in anticipation
of its general introduction it may not be out of character with this
little work to describe the process in detail.
Respecting the origin of the term fresco there are two opinions;
according to some the term is said to have been adopted because the
practice of it is used in the open air. Thus in the Italian language,
_andare al fresco_ signifies “to take the air;” or “to walk abroad in
the air;” but a more probable explanation is to be found in another
meaning of the word fresco, viz., “new,” or “fresh,” as applied to the
state of the plaster in which it is wrought. The artist traces his
design, colours it, and completely finishes in one day so much of his
picture as will occupy the wet plaster ground that has been prepared
for him, so that when the ground is dry, he may not retouch any part
of his work. This is the characteristic distinction of painting in
fresco--a method by which the painting is incorporated with the mortar,
and drying along with it becomes extremely durable, and brightens in
its tones and colours as it dries.
It will therefore be readily conceived that the artist in fresco has
to encounter difficulties of no ordinary kind; a few of them are thus
noticed by a writer in REES’S _Cyclopædia_:--“From the necessity there
is in the progress of this style of art, that it should be executed
with rapidity, and from the impossibility of retouching it without
injuring the purity of the work, the artist, unless he be endowed with
very extraordinary powers of imagination and execution indeed, is
obliged to prepare a finished sketch of the subject, wrought to its
proper hue and tone of colour, and so well digested, that there may
be no necessity for making any essential alterations in the design.
This, which is a very useful mode of proceeding in all fine works of
painting, is absolutely indispensable in fresco, to those who are
not determined to give the rein to their ideas, and leave as perfect
whatever may first present itself. There is no beginning in this, by
drawing in the whole of the parts at one time, and correcting them at
leisure, as is the custom with oil-painters, who may therefore proceed
to work without a sketch; here all that is begun in the morning must
be completed in the evening; and that almost without cessation of
labour, while the plaster is wet; and not only completed in form, but
also, a difficult, nay, almost impossible task, without a well-prepared
sketch, must be performed, viz., the part done in this short time must
have so perfect an accordance with what follows, or has preceded, of
the work, that when the whole is finished, it may appear as if it had
been executed at once, or in the usual mode, with sufficient time to
harmonize the various forms and tones of colour. Instead of proceeding
by slow degrees to illuminate the objects, and increase the vividness
of the colours, in a manner somewhat similar to the progress of nature
in the rising day, till at last it shines with all its intended effect,
which is the course of painting in oil, the artist working in fresco
must at once rush into broad daylight, at once give all the force in
light, and shade, and colour, which the nature of his subject requires,
and this without the assistance (at least in the commencement) of
contrast to regulate his eye; so that here, as has been said, a well
digested and finished sketch seems indispensably requisite.”
The custom of decorating walls with paintings is very ancient. Those
discovered by Belzoni, among the royal tombs of Egypt, prove the
existence of the art among the Egyptians many centuries before the
Christian era. There is also abundant evidence that it was practised
by the Etruscans and Romans. But the more common practice up to the
time of Augustus seems to have been to paint the walls of houses of one
single colour, and to relieve this with fantastic ornaments. According
to Pliny, Augustus was the first to suggest the covering of whole walls
with pictures and landscapes. About the same time a painter named
Ludius invented that style of decoration, now called _arabesque_ or
_grotesque_, many beautiful examples of which have been discovered at
Pompeii and other places. The invention of the Arabesque style, as its
name implies, has been improperly claimed for the Arabians of Spain;
whose religion forbidding the representation of animals, they employed
foliage, stalks, stems, tendrils, flowers, and fruit, in a variety of
forms and combinations, with which they adorned the surfaces of their
buildings. Hence the fanciful combinations of natural objects occupying
a flat surface came to be called Arabesque, although it differed so
much from the Mohammedan compositions as to contain animals real or
fabulous. That the term is badly chosen, especially as applied to the
fanciful enrichments on the walls of Pompeii, &c., will be seen from
the fact that such ornaments were invented and executed long before
the sons of Ishmael had learned to draw. The term grotesque is less
objectionable: it is derived from the subterranean rooms (grotte) in
the baths of Rome, in which those specimens of ancient art were found,
from which Raphael derived the plan of the beautiful frescos which
adorn the piers and pilasters of the arcaded gallery of the palace of
the Vatican, called, in honour of the artist, “Le Logge di Raffaelle.”
The practice of Fresco Painting may be conveniently considered under
the following heads:--1. The cartoon. 2. The preparation of the wall.
3. The process of painting. 4. The colours and implements. The methods
as adopted by different artists are of course subject to variation; but
as general principles are not altered by variations in those details
which conduce to the same end, so the following may be taken as an
accurate exposition of the practice of the art.
1. _The Cartoon._ Since the artist cannot without injury retouch a
fresco painting, it is necessary that every part of the design be
decided on by preparatory sketches finished of the full size, from
which the fresco may be transferred, by tracing to the wall. When the
painting is very large, the whole composition of the full size is
sometimes divided into two or more cartoons.
In the preparation of a cartoon, a strong cloth is stretched on a
frame, as if to be prepared for painting; paper is then firmly glued
on the cloth. When this is dry, a second layer of paper is attached
by glue. The edges of the separate sheets, where they overlap, are
scraped, so as to preserve an even surface. The surface is then
prepared for drawing with size and alum.[7] The drawing is made with
charcoal, and when finished is fixed by wetting the cloth at the
back with cold water, and then steaming the drawing in front. The
steaming is performed with a tea-kettle with two or three spouts, kept
boiling by the flame of a spirit lamp; by this means the charcoal is
incorporated with the melted glue, and a solid surface like that of a
picture is produced.
From this finished drawing the outline is traced on oiled paper. As
much of this working outline as can be finished in one painting is
then nailed to the wet wall, and the forms are again traced with a
sharp point, whereby an indented outline is produced on the soft
plaster. According to another method, the paper to be applied to the
wall is placed behind and in close contact with the finished cartoon;
the outlines of the latter are then pricked, and a similar pricked
outline is thus produced on the paper behind. This pricked paper is
then made the working drawing: it is fastened to the wall, and dusted
with a little bag filled with black or red dust; this leaves a dotted
outline on the wall. This method is sometimes adopted for small works,
and the advantage of it is that it leaves the surface of the plaster
undisturbed. The first mode is, however, generally preferred; since it
insures the best and most decided outline, and preserves the finished
cartoon uninjured.
Cartoons prepared for fresco may be seen in the National Gallery:
those at the head of the staircase are by Agostino Caracci. In one of
these (the Triumph of Galatea) the pricked outline is very apparent;
as also in the fragment of the Cartoon by Raphael, (the Murder of the
Innocents,) also in the National Gallery. In many celebrated Italian
frescos the indented outline, produced by tracing, is apparent.
In addition to the cartoon it is desirable to have a coloured sketch of
the whole composition.
2. _The preparation of the Wall._ The greatest obstacle to the
permanence of fresco painting is damp: hence, if the wall to be painted
is covered with old mortar, the ingredients of which are unknown, this
coat should be entirely removed until the solid brick or stone is laid
bare. The rough coat then applied is composed of river-sand and lime,
and of such thickness as is generally used in preparing the walls of
dwelling-houses. The surface of this coat should be rough, but not
uneven. Thus prepared, the wall should be suffered to become perfectly
dry and hard; the longer it remains in this state the safer it will be,
especially if the lime used was in the first instance fresh. In that
case two or three years should elapse before the process of painting is
commenced.
The preparation and seasoning of the lime is one of the essential
conditions of fresco painting. At Munich it is made and kept as
follows:--A pit is filled with clean burnt limestone, which is slaked,
and then stirred continually till it is reduced to an impalpable
consistence. The surface having settled to a level, clean river-sand
is spread over it to the depth of a foot or more, so as to exclude the
air, and, lastly, the whole is covered with earth. It is allowed to
remain thus for at least three years before it is used, either for the
purposes of painting (lime being the white pigment) or for coating the
walls.
The last preparation for painting on the mortar, is as follows:--The
surface is wetted with pure water, till it ceases to absorb. A thin
coat of plaster is then spread over that portion only which is to be
painted: the surface of this coat should be moderately rough. As soon
as it begins to set (_i. e._, in about ten minutes or so, according
to the temperature) a second thin coat is laid on, and the surfaces
are smoothed with a wooden trowel. Some painters like to work on a
perfectly smooth surface, in which case the last coat is polished by
applying a piece of paper on the surface, and passing the trowel over
it. When a small amount of roughness is required, a dry brush, or a
piece of beaver nap attached to the trowel, is passed over the plaster
in all directions.
3. _The process of Painting._ The wall being properly prepared, the
outline of the figures is to be traced with a sharp point on the
plaster, as before described. The artist commences his work when the
surface is in such a state that it will barely receive the impression
of the finger, and not so wet as to allow the colours to run or to be
liable to be stirred up by the brush. If the wall has been previously
well wetted, it will in general not dry too rapidly; but if in warm
weather the surface becomes too hard to imbibe the colour properly, a
small quantity of water is from time to time sprinkled over the surface.
The colours being ground fine in water, and the most useful tints
abundantly supplied, they are arranged in pots or basins, and several
palettes with raised edges are ready at hand to work from. A few pieces
of tile or some absorbent material are provided to prove the tints
upon, because all colours ground in water become much lighter when dry
than they appear when wet. The brick absorbs the water, and leaves the
colour nearly in the state in which it will appear upon the wall.
The first tints that are applied sink in and have a faint appearance;
it is therefore necessary to go over the work several times before the
full effect is produced: but after some time the last edition of colour
will not unite with that already applied unless the part be again
wetted.
At the close of a day’s work, any portion of the prepared plaster which
remains over and above the finished part is to be cut away, care being
taken to make the divisions at a part where drapery, or some object or
its outline, forms a boundary, for if this be not attended to, the work
will appear patchy. The next day, in preparing a new surface, the edges
of the previously painted portion must be carefully wetted so as to
ensure a perfect junction of all the parts of the painted surface.
At Munich the artists have a contrivance for arresting the drying of
the work should they be unable to finish the day’s allotted portion.
A piece of fine linen is wetted and spread over the fresh plaster and
painting, and pressed to the surface by means of a cushion covered with
waxed cloth.
Defects are sometimes remedied by cutting out the objectionable
portion, and painting it anew upon a fresh surface of plaster. In the
finished fresco, shadows are sometimes deepened, parts are rounded,
subdued, or softened by hatching in lines of the colour required, mixed
up with vinegar and white of egg. Crayons made of pounded egg-shells
are sometimes used to heighten the lights. But all these additional
amendments are highly objectionable; they impair the durability of the
fresco, and in the open air these retouchings are useless, because the
rain washes them away, whereas it has no influence upon frescos painted
without retouching.
4. _The Colours and Implements._ The colours employed in fresco
painting are few and simple. They consist chiefly of earths and a few
metallic oxides variously prepared. No animal and vegetable substances
can be used, because the lime would destroy them. The brushes are of
hog’s hair, but longer than those used in oil painting. Small pencils
of otter hair are also used; no other hair being found to resist the
lime. Pure distilled water ought to be employed in all the operations
of this art.
Such is the process of fresco painting, the details of which, after the
above statement, will be rendered more intelligible by the following
abridged account of a visit, by Mr. Andrew Wilson, to the royal palace
at Genoa, to see the Signor Pasciano paint a ceiling in fresco:--
The artist had prepared his tints upon a table with a large slate for
the top: they consisted of terra vert, smalt, vermilion, yellow ochre,
Roman ochre, darker ochre, Venetian red, umber, burnt umber, and black.
These colours were all pure, mixed with water only, and rather stiff.
He mixed each tint as he wanted it, adding to each from a pot of pure
lime, or from one containing a very pale flesh tint. A lump of umber
served to try his colours on. He used a resting-stick with cotton on
the top to prevent injury to the prepared wall, or _intonaco_, as the
Italians call it. The moment this surface would bear touching, the
artist began to work upon the figure, the outline of which had just
been traced. The head was that of the Virgin. The artist began with a
pale tint of yellow round the head for the glory: he then laid in the
head and neck with a pale flesh colour, and the masses of drapery round
the head and shoulders with a middle tint, and with brown and black
in the shadows. He next, with terra vert and white, threw in the cool
tints of the face; then with a pale tint of umber and white, modelled
in the features, covered with the same tint the part where the hair
was to be seen, and also indicated the folds of the white veil. All
this time he used the colours as thin as we do in water colours; he
touched the intonaco with great tenderness, and allowed ten minutes to
elapse before touching the same spot a second time. He now brought his
coloured study, which stood on an easel near him, and began to model
the features, and to throw in the shades with greater accuracy. He put
colour in the cheeks, and put in the mouth slightly, then shaded the
hair and drapery, deepening always with the same colours, which became
darker and darker every time they were applied, as would be the case
on paper for instance. Having worked for half an hour, he made a halt
for ten minutes, during which time he occupied himself in mixing darker
tints, and then began finishing, loading the lights, and using the
colours much stiffer, and putting down his touches with precision and
firmness: he softened with a brush with a little water in it. Another
rest of ten minutes; but by this time he had nearly finished the head
and shoulders of his figure, which being uniformly wet, looked exactly
like a picture in oil, and the colours seemed blended with equal
facility. Referring again to the oil study, he put in some few light
touches in the hair, again heightened generally in the lights, touched
too into the darks, threw a little white into the yellow round the
head, and this portion of his composition was finished, all in about
an hour and a half. This was rapid work, but it will be noticed that
the artist rested four times, so as to allow the wet to be sufficiently
absorbed into the wall to allow him to repass over his work. He now
required an addition to the intonaco; the tracing was again lifted
up to the ceiling, and the space to be covered being marked by the
painter, the process was repeated, and the body and arms of the figure
were finished.
On the occasion of a second visit, Mr. Wilson remarked that the
artist had cut away from his tracing or cartoon those parts which
he had finished upon the ceiling: that the tracing was in fact cut
into several portions, but always carefully divided by the outline
of figures, clouds, or other objects. These pieces are nailed to the
plaster, so as to fold inwards or outward for the convenience of
tracing the outlines. The artist was now about to proceed with a group
of figures. Having gone over the outline carefully with a steel point,
he waited till the intonaco became a little harder, and in the mean
time mixed up a few tints; he then commenced with a large brush, and
went over the whole of the flesh; he next worked with a tint which
served for the general mass of shadow, for the hair, and a slight
marking out of the features. He now applied a little colour to the
cheeks, mouth, nose, and hands, and all this time he touched as lightly
as possible. He then paused for ten minutes, examined his oil study,
and watched the absorption of the moisture.
The intonaco would now bear the gentle pressure of his fingers, and
with the same large brush, but with water only, he began to soften and
unite the colours already laid on. He had not as yet used any tint
thicker than a wash of water-colour, and he continued to darken in the
shadows without increasing the force or depths of colour. The artist
now increased the number of his tints; he made them of a much thicker
consistence, and he now began to paint in the lights with a greater
body of colour, softening them into the shades with a dry brush, or
with one a little wet, as was required. In drying, the water comes to
the surface and actually falls off in drops, but this does no harm,
although, as Mr. Wilson remarks, it sometimes looks alarming.
The effect of fresco painting is described as being exceedingly
beautiful. It does not require for the production of its general effect
those particular and concealed lights which the shining surface of an
oil-painting renders necessary. Fresco is seen entire in any situation
and by any light, even by artificial light, which perhaps shows it
best. Mr. Severn was much struck by the increased beauty and power
of the Caracci frescos at Rome by artificial light. Even a dim or
diminished light does not destroy their effect.
“It must have been for this reason that Raphael adopted fresco in
the Vatican, after he had made experiments in oil; for the rooms are
so ill-lighted, that oil pictures could never have been seen at all;
and it is surprising to find such fine works in such a place. Three
sides of the rooms are illuminated merely by the reflected light from
the great wall of the Sistine chapel, yet this beautiful and luminous
material of fresco is so brilliant in itself, that the pictures are
well seen. Nine of them were painted without a ray of real light, and
have always been seen in the same way. I think this is a very important
consideration; for as we have but a diminished light at any time, it is
most necessary to adopt a manner of painting suited to it, which can be
seen at all times.”
Fresco does not seem to be at all understood in this country; it is
generally confounded with scene painting; it is a common mistake to
suppose that the cartoons of Raphael are the same as his frescos. It
is often confounded with distemper painting, which is done on a dry
ground, and does not admit of richness of colour.
“This will be clearly understood (writes Mr. Severn) by those who
have had the good fortune to see Raphael’s and Guido’s frescos at
Rome, which for colour are exquisitely beautiful, and even powerful in
all the fascinations of this part of the art, presenting to us still
greater varieties than oil painting can pretend to; excelling in all
the delicate effects of atmosphere, from the gorgeous daylight, the air
of which you seem to breathe in a fresco picture, down to the silvery
flitting charm of twilight. In these particulars, it reminds us of
English water-colour effects. Then I should mention the magnificence
of fresco landscape, and of landscape backgrounds, particularly by
Domenichino, in which not only the characters, but the movements of
trees, are always rendered in a way which I have rarely seen in oil
colours.... Then I must remind you of the grandeur of colour and effect
in Michael Angelo’s frescos on the ceiling of the Sistine chapel. What
oil could ever have approached such things? When he said ‘that oil
painting was only fit for women and children,’ he meant on account of
the labour and difficulties of the material compared with fresco. We
are assured he performed this gigantic labour in twenty months, without
the usual assistance of colour-grinders or plasterers, but alone with
his own hand. There are on this ceiling fourteen figures, of at least
forty feet in stature, and nearly five hundred figures, the least of
which are double the size of life. While we regard this as the most
extraordinary example of individual human power, we must consider that
it was only in the simplicity and ease of the fresco material that
Michael Angelo could have accomplished such a stupendous work. The
preparation of oil colours, varnishes, &c., would alone have occupied
the twenty months.”
The small cost and great durability of frescos are not the least
of their advantages. It was feared that the smoke of London would
soon destroy our frescos, but Professor Hess stated that “if frescos
were painted in the open air in London, the rain would be the best
picture-cleaner.” Indeed, competent authorities agree that pure water
and a soft sponge are the best means for cleaning frescos from the
effects of smoke. That the change effected by time on the colours
is to increase their effect. The great enemy to fresco is a wall
constitutionally damp, in which lime in too new a state has been
employed, or new timber or imperfectly burnt bricks. The nitre which
sometimes accumulates on walls is also very destructive.
Nor are frescos such permanent fixtures as is generally imagined. Some
ingenious Italians have succeeded perfectly in removing large frescos
from one wall and applying them securely to another. The colours in
fresco do not penetrate very deep, and the thin layer of pigment and
lime of which the painting consists, may be removed by glueing several
layers of calico to the wall: a slight force is then sufficient to
detach the painting: it is removed to its new bed, and when firmly
attached, the cloths and glue may be removed by warm water.
* * * * *
We must now leave the Reader in possession of the dwelling-house which
we have endeavoured to build for him. If we have not _furnished_ it,
or described the modes in which the various articles of furniture are
made, it was not because the subject is devoid of interest, far from
it; but because we were anxious not to injure the completeness and
interest of the preceding details by attempting too much within the
limits of this little volume.
FOOTNOTES:
[7] The term Cartoon is derived from _curtone_, the augmentative of
_carta_, the Italian for _paper_.
LONDON:
SAVILL AND EDWARDS, PRINTERS,
CHANDOS STREET.
Transcriber’s Notes
In a few cases, obvious errors in punctuation have been fixed.
Page 28: “the standstones of which” changed to “the sandstones of which”
Page 141: “the vessel _e_” changed to “the vessel _c_”
Page 213: “upon the cieling” changed to “upon the ceiling”