which is wide enough to permit the hand to be introduced. I would here,
however, add, that even when it is too small for this purpose, the
restoration can be equally well effected as follows:--Make the core of
wet clay, or, better, of beeswax, then paste over it thin tough paper.
Cover this with gum-arabic solution, and set the pieces on it. When
dry, melt out the wax or clay.
Fish-gum, _colle de poisson_--that is to say, what is generally called
_sturgeon’s bladder_, which includes the bladder of several kinds of
fishes dissolved--is best for glass, marble, porcelain, and all kinds
of mending where the cement should not show. This, when combined with
oil, is _said_, if mixed with cloth-dust and fibre of wool or silk or
cotton, to spin up into thread.
MENDING GLASS
WITH SEVERAL ALLIED PROCESSES
APPROVED CEMENTS--SILICATE OF SODA
“_Glück und Glas
Wie bald bricht dass._”
“_Good luck, like glass,
Soon breaks, alas!
Yet skill can bring it so to pass
As to mend a fortune or a glass._”
--Old German Proverb.
Putty is naturally the first cement which suggests itself in connection
with the mending of glass, since this latter material is most familiar
to the world in the form of windows, although in many places--as, for
instance, Florence, where it is called _mastico_ and _pasta_--it is
little used or known. The word is from the French _potée_, which also
means a potful. It is very useful, not only for setting glass-panes,
but for filling holes in wood, and forms a part of certain mixtures as
a cement for moulding ornaments. It may be weak and brittle, or else
strong and very hard, according to the manner in which it is prepared.
It is commonly made by combining chalk in paste, with water, with
linseed-oil; other powders are also used. In America it is made with
pulverised soap-stone and oil. Its excellence depends on the quality
of the oil and the care with which it is kneaded. It should be kept in
a damp cellar, in wet cloth or under water. Should it dry and become
brittle, fresh oil must be added.
“_To take hard old putty from glass window-panes_, cover it with a
mixture of one part of calcined lime, two of soda, and two of water”
(LEHNER). Oxide of lead combined with oil makes an excellent but yellow
putty. It sets very hard.
The white or grey oxide of zinc combined with linseed-oil or
linseed-oil varnish makes a cement which is used for making glass
adhere to wood or metal.
_Thick lacquers_, such as copal or amber, may be used instead of common
varnish with better effect, and the composition is better when calcined
lime or oxide of lead are added. The excellence of the cement depends
on the degree to which the ingredients are amalgamated or rubbed in
together; and this rule holds good for all similar mixtures.
_Varnish_, or heavy or “flat” lacquer of copal or amber, forms of
itself a strong adhesive, with the only drawback that it takes a long
time to dry.
A VERY GOOD CEMENT FOR GLASS (LEHNER) is as follows:
Gutta-percha 100
Black pitch (asphalt) 100
Oil of turpentine 15
This is a glue of general application, and specially good for leather
and mending shoes.
The reader who would thoroughly study the subject of glass may consult
_Die Glas-Fabrikation_, a very admirable work by Raimund Gerner, glass
manufacturer; A. Hartleben, Vienna and Leipzig, price 4s. 6d.
Small triangles of sheet tin or iron are often used to fasten panes.
The mending of broken glass is in most cases much the same as that
of broken crockery or porcelain. The cement made from mastic, or
mastic combined with sturgeon’s bladder, or generally of silicate with
whiting, is the proper adhesive. As silicate of soda is simply liquid
glass, it can be employed to fill spaces or to make glass; but, owing
to its sticky nature, it is hard to manage. This may be often effected
by first preparing a layer of soft paper, on which successive coats of
silicate are laid. When dry the paper can be washed away.
SILICATE OF SODA has become of such importance that a French work on
mending fictile ware is almost entirely limited to its use as a binder,
when combined with whiting. _Water-glass_ was long supposed to be a
modern invention, till some one found it described in Van Helmont’s
works, A.D. 1610. But I have found it also in the _Joco-seriorum
Naturæ_, 1545; in the _Magia Naturalis_ of Wolfgang Hildebrand,
which is of the same time; and, finally, by _Paracelsus_ (_Liber de
Præparationibus_), where he describes it as _Destillatio Crystalli_.
And the author of the _Joco-seriorum_ speaks of soft glass as a thing
which had been treated by several writers.
According to WAGNER there are three kinds of soluble glass--(i.)
the soluble potash glass, 45 silex, 3 charcoal, 34 carb. potass.;
(ii.) soluble soda glass, 100 pts. quartz, 60 cal. sulp. soda, 15 of
charcoal; (iii.) double soluble glass, 100 quartz, 22 cal. soda,
28 carb. potass., 6 wood-coal. Water-glass combines well with any
“indifferent” powder, such as powdered glass, to make a strong cement.
To powder glass, heat it red-hot, drop it into cold water and pulverise
it. It will become as fine as flour, and in this state combines with
gum-arabic, or glue, or gums to make a powerful glass-mender. Mixed
with powdered glass, oxide of zinc, or whiting, powdered marble,
calcined bone, plaster of Paris, wood-ashes, &c., it can be worked like
putty. Mixed with colours it is used for stereochrome painting, a kind
of fresco.
Missing pieces of glass, such as leaves from a chandelier, can be
easily replaced with water-glass, and all cracks or defects glazed over
with it.
This mending is allied, however, to certain processes in art which are
so interesting that I venture on a description of them.
A great deal of mending and restoring in glass can be effected by
means of the blow-pipe and spirit-lamp or gas-flame. Difficult as
this may sound, it is not only an easy, but also a very curious and
entertaining, occupation. In any city an expert or workman may be found
who would give a few lessons. I have very often been impressed with
the fact that so little artistic invention or originality is found in
glass-work. Even the far-famed Venetian work is extremely limited, and
“mannered” or conventional, compared to what it might be.
The following is an old recipe for repairing glass:--Take finest
powdered glass, best mastic, with equal parts of white resin and
distilled turpentine. Melt all well together. To use, gradually warm
it and then apply.
Quicklime and white of egg, intimately rubbed into one another on a
flat surface, make a good cement for ordinary glass or pottery.
The cement of _gum-arabic_ is much stronger when made as follows:--Take
gum-arabic and dissolve it in acetic acid (vinegar) instead of water.
It must be melted in a hottish place, as it will in that case be much
better. The finest quality of sheet-gelatine makes a transparent glue,
invaluable where colour is to be avoided.
TO MEND A CRACKED GLASS BOTTLE OR DECANTER.--Heat the bottle, pressing
in the cork, till the hot air within expands the cracks, which must
be at once filled with the liquid glass. Then, as the water-glass is
driven in by the pressure of the outer air, as the bottle cools the
cracks are closed.
You cannot well mend a broken looking-glass, but something can be
done with the large pieces. Varnish or paste a piece of paper and lay
it on the quicksilver. Then with an American glass-cutter, price one
shilling, or a diamond-cutter, divide them into squares for small
mirrors. Two of these of equal size can easily be converted into a
folding kaleidoscope (not described by BREWSTER in his work on the
Kaleidoscope). Lay the two pieces face to face, and paste over the
whole, on the quicksilvered side, a piece of thin leather or muslin.
When dry, with a penknife, cut a slit down between the two on three
sides. It will then open and shut like a portfolio. This may serve
as a travelling, looking or shaving glass, but it is very useful to
designers of patterns. Place the glass upright on a table at a right
angle, or more or less, and lay between the mirrors any object or a
pattern, and you will see it multiplied from three to twelve times,
according to the angle. Beautiful variations of designs can thus be
made, _ad infinitum_. They may be used as reflectors, when placed
behind a light.
Take such a piece of looking-glass and lay a piece of paper on the
back, and then with an agate or ivory point write or draw on it, but
not as hard as to break the silvering. Then turn it to the sun or a
strong light, and let the reflection fall on a white surface. Though
nothing be perceptible on the face of the mirror, the writing will
appear in the reflection.
Glass is engraved as metal is etched; with this exception, that,
instead of sulphuric or nitric acids, fluoric acid is used. Both glass
and _china_ can also be directly etched with a steel point, aided by
emery powder; which latter art I have never seen described, but which
I have successfully practised. It is fully set forth in my forthcoming
work on “One Hundred Arts.”
Malleable glass, or at least that which does not break easily when let
fall, is prepared by dipping the objects made from it, while quite hot,
into oil. I conjecture that panes of window-glass thus prepared would
not be broken by hail, as I have observed that plate-glass is not.
It sometimes happens that goblets of thin glass--especially those which
have had a peculiar kind of annealing or tempering--ring beautifully
when blown on so as to vibrate them. The effect is almost magical on
one who hears it for the first time. I mention it that the reader
may, when he finds old Venetian or any other thin glass goblets for
sale, see if there be not among them a finely ringing one. An organ
could be thus made to play by wind. With regard to music on glass,
take any ordinary bottle, and by rubbing on it a cork a little wetted
you can, with a little practice, produce a startling imitation of
the chirping, and even warbling, of birds. I knew one who could thus
imitate to perfection nightingales and call forth responsive songs. The
effect depends in a degree on the quality of the cork, and also that
of the glass. With a violin-bow very musical sounds may be drawn from
the edge of a pane of glass. It seems as if these methods might also
be developed into musical instruments. It is well known that tubes of
glass suspended when a candle is placed beneath them give forth musical
sounds, often of great richness and strength. There are also the
musical glasses, which may be played in two ways, either by rubbing the
edges with a wetted finger or by filling the glasses more or less with
water till an octave is formed, and then tapping them with a stick of
wood. All of which has, indeed, nothing to do with mending glass, yet
which may not be without interest to those who wish to learn all its
qualities.
Among GLASS CEMENTS in common use which can be recommended are the
well-known Polytechnic, also the Imperial Liquid Glue (no heating
required), Hayden & Co., Warwick Square, London. There is also a very
good glass cement made and sold by Keye, filter-maker, Hill Street,
Birmingham.
The Venetians made ordinary glass goblets very beautiful by painting
on them in relief with a substance which I suspect was in some cases
a form of silicate, or else with a kind of paint which was not enamel,
yet which seems to have been partly vitreous. It rather resembles oil
paint with glass powder, but I doubt if it was this.
Working in glass implies the mending and restoration of stained-glass
windows; that is, of painting on glass and a study of designs. Of all
this there is almost a literature. Among other works I can commend _A
Book of Ornamental Glazing Quarries_, by A. W. Franks, £1, 1s.; _Divers
Works of Early Masters in Ecclesiastical Decoration_, by Owen Jones,
£3, 10s.; _Westlake’s History of Stained Glass_, vol. i., _Fourteenth
Century_, 13s. 6d.; vol. iii., _Fifteenth Century_, 18s., published by
Batsford, 52 High Holborn. At Rimmel’s, in Oxford Street, the reader
can generally obtain these, and all works on similar subjects at prices
much below the original cost.
A MENDING CEMENT FOR GLASS is made as follows:--
Common cheese 100
Water 50
Slacked lime 20
This is found in many books of recipes. It must be observed that the
cheese is to be for sometime carefully pounded with the water till
quite soft, and the lime then very quickly stirred in. This is not only
useful to mend glass, but can be applied to many other purposes. The
cheese is best when fresh.
CASEINE (or pure cheese) can be combined with ease with liquid silicate
of soda (LEHNER), and thus forms a very strong cement for porcelain or
glass, or any other material. Fill a flask with one-fourth of fresh
caseine to three-fourths of silicate, and shake it thoroughly and
frequently.
Another formula is as follows:--
Caseine 10
Silicate of soda 60
This must be used very promptly, and the article mended dried in the
air.
A CEMENT which may be used in several combinations is made by
dissolving fresh acidulated caseine (made by adding vinegar to milk,
and carefully washing the deposit) in a very little caustic lye. It
must be kept corked in bottles.
These _caseine_ or cheese or curd cements hold well, but do not well
resist water, except in powerful combination.
The excellence of cements depends to a great degree on the quality of
the materials and the scrupulous observance of care in making. Thus for
the following, for glass:--
Glue 200
Water 100
Calcined lime 50
in which we have one of the commonest and oldest formulas, the value
depends on “the make-up” that is, the glue must be left in cold water
for two days, then boiled in a _balneum mariæ_, or a double kettle, in
lukewarm water; that is, it must not boil, or the glue will be weakened.
The so-called DIAMOND or TURKISH CEMENT, for glass or any other fine
work, has been known since early times as incredibly strong. Its
formula, according to Lehner, is as follows:--
I. Sturgeon’s bladder 20
Water 140
Spirits of wine 60
II. Gum-mastic 10
Alcohol 80
III. Gum-ammoniac 6
These are three separate portions, No. I. being prepared by warming
and filtering. The gum-ammoniac is reserved from the others, and added
_after_ they are mingled.
A STRONG BASE FOR A CEMENT FOR GLASS, as well as wood or stone, is made
by gradually stirring finely sifted wood-ashes into silicate of soda,
or strong acid glue, till a syrup-like substance results. In America
the best ashes for this purpose are those of the hickory. Perhaps beech
wood yields them equally good.
There is a DIAMOND CEMENT which is of special value to attach gems to
rings or metal, to make coral or pearl or ivory adhere together, and,
in short, for all fine work where a very strong adhesive is required.
It is as follows:--
Sturgeon’s bladder 8
Gum-ammoniac 1
Galbanum 1
Spirits of wine 4
The sturgeon’s bladder is cut into small pieces and steeped in the
spirits, and the rest, in solution, then added. It must be warmed again
when used.
As this cement will bear long exposure to moisture before being at
all injured by it, it can be used as a medium for painting on glass,
and thereby producing effects very little inferior, either as regards
beauty or durability, to glass itself. The experiment can be easily
tried, as any chemist can make up the recipe. When finished, the
painting can be coated with liquid silicate of soda, which will give it
all the property of glass.
A LIME CEMENT FOR GLASS is made as follows:--
Calcined lime 30
Litharge 30
Linseed-oil varnish 5
JEWELLERS’ CEMENT. Extremely strong:--
Fish-glue solution 100
Mastic varnish (pure) 50
The fish-glue must first be dissolved in spirits of wine.
TO JOIN GLASS AND METAL, &c.--Stir slacked and powdered lime in hot
glue. This sets as a very hard substance. It can be extensively
modified and varied for many substances, and used for painting.
CEMENT FOR GLASS:--
Gum-arabic 50
Sugar 10
Water 50
Oil of turpentine 10
The gum, sugar, and water are first carefully combined, and then the
turpentine well stirred with the mixture.
SALLE’S CEMENT FOR GLASS:--
Muriate of lime 2
Gum-arabic 20
Water 25
Not commended by LEHNER, as being too soluble. TO CLOSE BOTTLES:--
Powdered resin 6
Caustic soda 2
Water 10
To be thoroughly mixed and left for several hours. Before using, stir
well into it eight to nine parts of calcined plaster of Paris. This
will in half-an-hour take firm hold or “set,” and is waterproof. A good
filler for cracks.
The reader who desires to be perfectly informed as to glass in all its
relations can obtain, by application to J. BAER, Rossmarkt, Frankfort
on the Main, Germany, a catalogue which is perhaps the most extensive
on the subject ever published.
Coloured or stained glass windows may be repaired or made by the
following process, which has the advantage of being quite as durable
as any in which the colours are burned in:--Take two panes of glass,
and paint on one your pattern with fine varnish and transparent colour
mixed. When dry, go over the whole, with a broad, soft brush, with a
liquid mastic cement, which must be quite transparent and thin. Any
transparent strong cement will serve, but it is advisable to use the
mastic in all cases as a narrow border and at the edges. If you have an
engraving, especially one on very soft spongy paper, take a pane of
glass, cover it with a coat of varnish, and just before it dries press
the engraving face down, on it. When quite dry, with a sponge slightly
damped and the end of the finger, peel away all the soft paper, leaving
the lines of the engraving. These may now be coloured over, with even
very little skill and care. A very good effect may be produced, so
that a very indifferent artist can in this way produce very tolerable
pictures. Then, to better preserve this, double it with the other pane.
By painting and shading also on this _second_ pane, as I have
discovered, very beautiful and striking effects of light and shade can
be developed, so that this forms, as it were, a new art by itself. This
will remind the reader of the porcelain lamp-shades, which so much
resemble pictures in Indian ink; but the effects of the double panes
are more singular and far more varied. There may be even a third pane
employed. As the materials for this art are far from expensive, and
as it is extremely easy, I have no doubt that it will be extensively
practised. Protecting one glass picture by another is not a new art;
but I am not aware that the obtaining a series of lights by thus
reduplicating the panes has been practised.
A modification of it is as follows:--Cut out several panes,
corresponding to the size of the two glass covers, of quite transparent
paper or parchment, prepared by rubbing with oil or vaseline, lard, or
the like. Paint on these the required modifications of the picture.
The advantage of this is, that a great many shades can thus be given
in a thinner space, creating an astonishing effect. As this is not at
all a mere imitation of stained glass, and as it produces effects not
to be found in the latter, it may rank as an art by itself. The chief
of these effects is _relief_, especially shown in the human figure.
But the most extraordinary are the variations of chiaroscuro which
it affords, by availing himself of which the artist may create or
obtain striking suggestions for oil or _aquarelle_ pictures; for these
transparencies can be so infinitely and ingeniously varied that no one
can fail to derive from them many ideas.
This may be tested by simply preparing any picture, say of a statue,
a castle on a rock, or a face. Cut out from sheets of the same size
in very transparent paper a series of shadows adapted to it, and
adjust them. They may be all in monochrome or one colour, or in many
hues. They may range, with proper care, from almost imperceptible
shadow to opaque black. By beginning with only two stencils or shaded
pictures--for as regards these the artist must be guided by his own
skill--and gradually increasing the number, the proper adjustment
will soon be found. I advise the beginner in copying to proceed
from monochrome to two colours before attempting many. Teachers in
_aquarelle_ will find that such copies are--after a certain degree of
proficiency shall have been obtained--much superior to those commonly
used, as they come nearer to nature.
The most perfect form of this curious art is an improvement which,
I believe, is my own invention. This consists of introducing leaves
of painted _mica_ between the two glasses. In this way four grades
or tones of colour and light and shade can be made in a picture.
Mica-leaves can be made into one by using mastic cement. Rub the edges
with emery-paper to roughen them.
As I have already intimated, the materials for this work are so cheap
and the process so easy, that all which I here assert may be at once
verified by the outlay of a few shillings, with a few hours of time. It
is, in another form, the same thing as arranging lights around a statue
in a dark room, but adapted to all kinds of pictures.
As a Latin poet has declared, “It is an easy thing to add to arts,”
when a beginning has once been made (“_Inventis facile semper aliquid
addere_”), so I will add to this a curious discovery in glass made by
me in Venice a few years ago. I was being taken by Sir AUSTIN LAYARD
over his celebrated glass-factory. It was he who, with the aid of
Sir WILLIAM DRAKE, _first_ revived the almost forgotten manufacture
of glass in Murano. While standing with him by a furnace watching a
workman skilfully forming ornaments in glass, it suddenly occurred to
me that the Chinese were said to have possessed in remote times an
art, now lost, of making vases or bottles which appeared externally
to be quite plain, but on the surface of which, when red wine was
poured in, patterns or inscriptions appeared of the same colour. It at
once occurred to me that this could be perfectly effected by making a
bottle, on the interior of which the ground should be of considerable
thickness, say half-an-inch, while the inscription or pattern would be
no thicker than ordinary window-glass. Then if the whole exterior were
to be lightly ground on a wheel or sandpapered, the difference between
ground and pattern would not be perceptible until red wine or some
highly coloured fluid were poured in, when the pattern would at once
show itself.
Sir AUSTIN LAYARD was so much struck by the suggestion that he sent at
once for his foreman, Signore Castellani, who said that he had heard
of such bottles, but always supposed it was a fable. He, however, at
once admitted that they could be made as I proposed, but added that
the expense would be so great as to render the invention practically
useless.
It has, however, since occurred to me that such bottles could be made,
and cheaply, as follows:--Take a Florence flask, and divide it into two
parts with a diamond, using a saw for the bottom. Then on the sides
within place the ground. It could be made of silicate of soda and
powdered glass or flint, or even of white wax, hardened with powdered
glass. Close the bottle with silicate, and grind the whole.
When any glass has been broken and mended, the fracture still
discernible may be thus concealed by grinding the surface, and in many
cases by surrounding it with a ring or tube of metal, also by one of
silicate, or with an ornament formed with it.
A glass stopper when too large can be easily filed down to fit. Should
the neck of the bottle be too narrow, it can also be enlarged by the
same process. When the rim of a goblet is fractured, it can be ground
down on a grindstone. I have done it with a file.
A pane of glass can be somewhat rudely cut into shape with a pair of
strong scissors, under water. In this, as in other things, practice
leads to perfection.
An old method of effectually closing bottles of wine was as
follows:--The edge of the opening on the top was ground down on a
stone, and a small disc of glass was exactly fitted to it. Heat was
then applied till both were in partial fusion and the cover was welded
to the bottle. A little powdered glass would aid the fusion, or it
could be effected with silicate without heating. The process is the
same as using glass stoppers, rather sunk in, and sealing up with
silicate.