LEATHER MOSAIC
Until recently it seemed as if this pleasing art would have to remain the
monopoly of a limited number of professional craftsmen working with
numerous tools, and reckoning a ten years’ apprenticeship necessary to the
attainment of proficiency in their craft. But although there is small
likelihood of amateurs entering the domain of the followers and emulators
of artists such as John Reynes, Florimond Badier, Monnier, Padeloup and
Jubert, Mons. Eugène Aumaître has invented a simpler process of leather
mosaic, for which fewer tools are required and which is within the reach
of artist and amateur alike. The following pages contain the result of the
study of his method, with the addition of some observations based on the
practical experience of the author.
LEATHER FOR GROUNDWORK
Any skin may be used for the groundwork of leather mosaic, but morocco,
and especially the kind called Cape morocco, is generally preferred,
because of the grained surface which shows up the inlaid decoration to the
best advantage.
Other skins, however, with either dull or glossy surfaces make good
backgrounds for mosaic decoration, and as they are generally fawn
coloured, they may first be stained to produce shaded groundwork very
attractive in effect.
The old masters of leather mosaic made great use of fawn-coloured calf,
occasionally adding a touch of coloured lacquer to bring out the light
parts of the design.
PREPARATION OF THE LEATHER FOR THE GROUNDWORK
The first necessity in working leather mosaic is to have a flat and rigid
surface to work upon; it is indispensable therefore, when the leather is
not in itself sufficiently thick and firm, to stretch it on cardboard.
This rather troublesome preparatory process is best confided to an expert;
we will, however, describe it for the benefit of those preferring to
execute it themselves. A strong, smooth piece of cardboard called
millboard is taken, and the edges rubbed down with glass paper. A thin
coat of paste is applied on one side of the board and allowed to dry.
[Illustration: FIG. 18.——PARING KNIFE]
[Illustration: FIG. 19.——PARING KNIFE]
The edges of the leather must now be thinned so that they will more
readily stick when turned over and pasted under the board, and also to
avoid the unevenness which the normal thickness of the leather would
produce underneath. A paring-knife with a broad, flat, very sharp blade
(Figs. 18 and 19) is used for this purpose; its manipulation is difficult
and requires long practice. The handle is held against the palm of the
hand, and the fingers extending over the blade cause it to penetrate the
leather superficially by a more or less strong pressure, the object being
to take off shavings from the back of the skin, increasing towards the
edge until the edge itself is reduced to the thickness of a cigarette
paper.
[Illustration: FIG. 20.——PARING LEATHER]
The leather is placed surface downwards on a lithographic stone or a slab
of marble. It is held stretched with the left hand, the fingers being
extended over it on the face of the stone, and the thumb pressed against
the side leaving the part just in front of the fingers free to be pared
(Fig. 20). It is of the first importance for the success of this operation
that the leather should be kept well stretched. The knife is held almost
horizontally to avoid cutting into the leather at too sharp an angle, and
is worked from left to right towards the edge.
The leather is then fastened to the cardboard by pasting either the whole
of it or only the edges, which are turned underneath. In any case ordinary
paste should be used; seccotine or glue would sink into and harden the
leather, making the subsequent outlining process difficult.
When the piece of leather is so large that it would cause the board to
warp when it dries, some paper should be pasted on the other side of the
board, which will keep it flat by drawing it in the opposite direction.
[Illustration: 8. BROWN LEATHER BINDING, CUT AND ENGRAVED, WITH PUNCHED
BACKGROUND. _GERMAN MS. CHRONICLE OF EVENTS._ GERMAN, 15TH CENTURY.]
The work is then put into the press or under heavy boards. It is important
that this should always be done after paste has been used. When it is too
large to put into a copying-press, it should be laid upon a flat table and
a sheet of nickelled or very smooth zinc placed against the part to be
decorated. The cardboard known as _Carton Jacquart_ may be substituted for
the zinc, but there is a risk that the moisture of the paste penetrating
the leather may cause it to swell, notwithstanding its glaze. The zinc
plate or the board should not be smaller than the leather, for in that
case the pressure would produce a ridge round its edge.
The groundwork is ready to receive the ornament as soon as it is dry. The
different methods of working mosaic will now be explained in turn.
MONOCHROME MOSAIC ON CALF
In this style of decoration the leather used for the inlaid design is
white or very light in tone, and may be dyed subsequently to present the
appearance of a mosaic made of variously coloured leathers.
LEATHER FOR INLAYING
The skins sold for this purpose are split sheepskins. Their extreme
thinness renders them liable to stretch a great deal, and therefore they
are most difficult to cut out in any desired shape. To obviate this
difficulty, the back of the leather is pasted over, and it is then
stretched on a board and fastened with drawing-pins to prevent it from
shrinking as it dries. But there is another and a better method——that of
mounting the leather on paper.
MOUNTING THE LEATHER ON PAPER
Some paste is made of very light and smooth flour, diluted with half the
quantity of water and beaten to a cream. The water is added in small
quantities while the mixture is being stirred. Canson paper, or some other
strong drawing paper, is pasted over the whole surface of the leather, so
that it adheres lightly, and can be removed afterwards without difficulty;
it is then placed under boards and allowed to dry thoroughly.
TRACING THE DESIGN ON THE PAPER
The design is traced by means of carbon paper on the paper lining of the
inlay leather. A hard pencil should be used in order to produce very sharp
lines.
CUTTING OUT THE DESIGN
Cutting-out knives should possess a keen edge and a small blade, and
should be so shaped that they can be turned freely in any direction. The
knife illustrated in Fig. 21 combines all these qualities. It consists of
a very fine double-edged blade, set loosely into a slit in a hard wood
handle and secured with a few turns of thread; a piece of leather over the
whole (A) keeps the blade in its place. The handle being loose, it is
possible to give any minute movement to the blade, which can also be taken
out for sharpening when necessary. It must be kept as sharp as a razor.
The extreme fineness of this blade facilitates cutting out the delicate
parts of a design, but if handled too vigorously it is apt to get out of
shape. The second tool (Fig. 22) is a stencil-cutter’s knife, and is very
similar to the one described above except in size. It is usually sold
mounted in an ebony slide bound round with copper wire, but can with
advantage be mounted as in Fig. 21, in a split hard-wood handle.
One little known tool deserves mention for its flexibility and lightness.
This is a small scraper shaped like an unslit pen, the blade widening from
the point in two very fine edges like the head of a pike. It is used by
photographers and miniature painters, and is sold by the dozen in small
boxes. When in use it is firmly fixed in a small pen-holder so that it
does not turn when pressed upon (Fig. 23).
[Illustration: CUTTING-OUT KNIVES: (A), FIG. 21, FIG. 22, FIG. 23]
The special knife illustrated in Fig. 17 is sometimes recommended, but it
is better adapted to cutting out thick skins for open-work decoration, as
the point of the blade is not sufficiently fine for use on thin leather.
[Illustration: FIG. 24.——CUTTING OUT INLAY]
The leather to be cut out is placed on a sheet of the cardboard used in
mounting drawings, which is firm, but at the same time easily penetrated
by the point of the tool. The nature of the board on which the leather is
laid is important, for to ensure a clean cut, the tool, as it pierces the
leather, must not encounter a veined surface such as that of wood, which
might deflect the point. The three middle fingers of the left hand hold
the leather mounted on the paper upon the board, the thumb and little
finger supporting the whole underneath (Fig. 24). The part which is to be
cut is turned towards the knife by the left hand, the right hand being
held in a fixed position with the knife, slightly inclined to the right,
cutting the leather as it is presented by the other hand. The lines must
be cleanly cut in order that the subsequent operation of outlining may be
successfully accomplished. With every care in cutting out, it may
sometimes be found in detaching the cut portion that a small thread of the
leather remains unsevered. In this case it should be neatly cut through,
and on no account may it be pulled to make it give way, which would result
in spoiling the design by either tearing or stretching the leather. When
cutting out a design on a large scale it is not possible to hold the work
in the manner just described; a part of the design to be cut out is
therefore placed flat on a large sheet of cardboard on a smooth table and
can then be turned about as required under the point of the knife.
[Illustration: 9. COVER OF CASE FOR A CUP IN WOOD COVERED WITH LEATHER,
_CUIR BOUILLI_, EMBOSSED, PAINTED AND GILT. ITALIAN, ABOUT 1500.]
When the inlay is of white or very light leather, it is extremely
difficult to conceal any joins occurring in the middle of lines; care must
therefore be taken that there are as few joins as possible, and that they
are arranged at points where they will easily disappear in lines of the
design going in an opposite direction.
The centre of the design should be cut out first, and then the outer
lines, reserving the more delicate parts, such as flower stems, for the
last.
PASTING THE INLAY ON THE GROUNDWORK
When the inlay is of a nature that does not require placing in any very
exact position, as for instance a spray of flowers, it will be sufficient
to lay it on the groundwork and mark the principal points. When it is to
occupy a definite position, forming the framework of a design, for
instance, it is laid upon the groundwork exactly in the right place and
then given a sharp turn in a copying-press, great care being taken that
it does not get displaced during the operation. Owing to the thickness of
the supporting paper, this will be sufficient to mark the outline of the
design on the groundwork. Some very smooth starch paste is then applied
with a flat brush on the exposed side of the cut out leather, care being
taken that every part, however small, is thoroughly pasted. To facilitate
this and to prevent the leather curling up when pasted, it should first be
fixed to a board with drawing-pins.
The portion of the ground which is to receive the inlay is damped with a
soft sponge; the inlay is then placed in position and pressed down with
the palm of the hand, a modeller being used for the finer parts. If it
should become displaced, the greatest care must be used in correcting it.
With the small pincers used by artificial flower-makers, the minutest
pieces of leather can be taken up and replaced after being repasted, if
necessary.
SETTING IN THE INLAY
The next process is that of setting the inlay into the groundwork, so that
no relief remains. This is done with the help of a roller with a long
wooden handle held in both hands and pressed against the shoulder, as
illustrated in Fig. 25. The paper on which the inlay is pasted plays an
important part in this operation; the greater its thickness, the greater
will be the pressure attainable, and the deeper the penetration of the
inlay into the damp background.
At first the roller is worked lightly with one hand only to ensure the
uniform adherence of the inlay, the movements being short, and repeated
several times over the same spot. When afterwards pressing heavily over
the whole surface, a piece of thin, tough paper between the roller and the
work will prevent the inlay from curling up, and the paper may be lifted
from time to time to see that nothing is out of place.
[Illustration: FIG. 25.——USING ROLLER TO SECURE ADHESION OF INLAY]
When the work is not too large, it is easier and more effectual to use a
copying-press instead of a roller for this operation, which is then
carried out in the following manner: A piece of felt is laid in the press,
and over it a sheet of very smooth or nickelled zinc, or, failing this, of
_Carton Jacquart_. The work is then laid on it and covered with a second
sheet of nickelled zinc and some pasteboards. The press is screwed up as
tightly as possible.
The work must not remain in the press, as if allowed to dry completely,
the subsequent removal of the paper pasted to the inlay would become
extremely difficult. To effect this removal, the paper is dabbed with a
damp sponge until it is ready to come off. A point of the pincers is
inserted underneath the paper which, if sufficiently soaked, should easily
come away when the tool is slid gently along. The paper, as it becomes
freed, should frequently be cut off with scissors to facilitate the
handling of the tool. The leather, being damp, may possibly become unstuck
and stretched during this process. It must then immediately be repasted
and replaced, and the stretched part reduced to its original size by
gently pushing it together with the modeller. Should it be found
impossible to reduce it thus, the part that is out of shape must be cut
off and joined on again. When the paper has been removed, the whole
surface is carefully washed over, wetting it as little as possible, so as
not to cause the mosaic to become unstuck. The work is then placed in the
press, or under boards, until it is perfectly dry.
OUTLINING THE MOSAIC
Outlining is the most delicate process in leather mosaic. When well
carried out it should be impossible to distinguish the line where the
inlay joins the groundwork. The extreme edge of the inlaid leather is
pressed into the groundwork by means of a tool invented by Mons. Aumaître,
producing a fine line the breadth of the edge of the tool selected. This
tool, called an outliner (Fig. 27), has two blunt ends, one rounded and
the other square, and is flat on one side and rounded on the other. The
rounded side of the tool affords extra pressure, and should therefore be
placed on the inner side of the line so that it serves to increase the
depression of the edge of the inlay. It is best to work the outline with
the cold tool first, and then to go over it again with the tool heated.
The inlay is lightly damped round the edges, and the round end of the
tool is placed half on the inlay and half on the groundwork. The tool is
held first inclined backwards (as in Fig. 26) and then brought with
pressure to a perpendicular position (Fig. 27). This will make a groove
into which the edge of the inlay will disappear. The square end of the
tool is used for straight lines. Great care must be taken in placing the
tool correctly; no portion of the inlay may protrude beyond the flat side
of the tool, as any particle of the edge, however minute, which is not
sunk in the groove would have to be cut off. If the edge of the inlay does
not extend up to the tool, the error is still more troublesome to correct,
more particularly when the leather is of a delicate colour, on account of
the difficulty of matching the exact shade for joining it.
[Illustration: FIG. 26.——FIRST POSITION OF OUTLINING TOOL]
[Illustration: FIG. 27.——SECOND POSITION OF OUTLINING TOOL]
After this operation the edge of the outlining tool (Fig. 28) is inserted
in the groove thus formed, and worked with a short up and down movement. A
ruler will serve as a guide in working straight lines. The round side of
the tool is held slightly inclined towards the edge of the inlay. The
wheel illustrated in Fig. 29 may also be used, but requires great sureness
of hand for its successful manipulation. Gouge-shaped outlining tools with
curves of different degrees (Fig. 30) are useful for little curved lines
which are otherwise difficult to work; also the tool represented in Fig.
31, for the lettering on bookbindings, etc., where the lines require to
be sharply finished. It must, however, rest with the artist to select the
tools he considers most suitable for his work.
[Illustration: FIG. 28.——GOUGE OUTLINER.
FIG. 29.——OUTLINING WHEEL.
FIG. 30.——GOUGE OUTLINER.
FIG. 31.——STRAIGHT OUTLINER.]
When the outline has been worked with the cold tool, a hot one is used to
go over it again to ensure perfect adhesion, and to give an attractive
brown tint to the lines. The end of the outliner is heated over a
spirit-lamp to a degree at which it can still be comfortably held in the
hand, and used as before. If the tool does not run smoothly, owing to the
elasticity of the edge of the inlaid leather, the latter may be lightly
damped with a brush. It will at first be found difficult to keep the tool
at the right heat. As a groundwork, calf with a smooth surface is more
sensitive to damage from an over-heated tool than split sheepskin. It is
useful to paste some of the inlay leather upon a spare piece of the
leather of the groundwork, with which to test the heat of the tool. If the
tool be too hot, it will burn and penetrate the leather without pressure.
It can be cooled to the desired temperature on a wet sponge.
The next process in leather mosaic is that of colouring, which is dealt
with in Chapter IV. It then only remains to give the finishing touch to
the work by passing a polishing iron (Fig. 32) over the surface, to polish
it and make it perfectly even. The tool is heated by holding the part
which does not come in contact with the leather over the flame of a
spirit-lamp. The polished side should frequently be well rubbed on
flannel, and should any portion of its surface become dull, the polish can
be restored with fine emery paper. The polishing iron, when heated, is
held in the right hand and worked with little stroking movements, bringing
first the end and then, by lowering the handle, the back of its polished
surface in contact with the leather. The various positions of the tool
during this operation closely resemble those of a vessel when it is
pitching.
[Illustration: 10. COVER OF WORK-BOX OF WOOD COVERED WITH EMBOSSED
LEATHER, _CUIR BOUILLI_. GERMAN, 16TH CENTURY.]
[Illustration: 11. POWDER-FLASK OF WOOD COVERED WITH LEATHER, _CUIR
BOUILLI_, CUT AND EMBOSSED. ITALIAN, 16TH CENTURY.]
POLYCHROME MOSAIC
[Illustration: FIG. 32.——POLISHING MOSAIC]
This style of decoration consists of different coloured leathers arranged
upon a ground, and is the only one that can properly be called leather
mosaic. The work of marking it out is a lengthy one and demands scrupulous
exactitude. A finished design is first painted in water-colours and marked
with letters which are repeated on the pieces of coloured leather, so
that the exact place is indicated which they are to occupy in the design.
It is important in this style of mosaic to obtain a very correct tracing
of the design on the groundwork. On a smooth and light ground the
tracing-point lightly worked will be sufficient; when the ground is dark
or has a grained surface, red or white transfer paper should be used. The
most satisfactory method of marking the design is by impressing a stencil
of thick paper, but it cannot be employed with morocco leather for fear of
crushing the grain too much. A thick stencil, however, carefully used
without exerting great pressure, may give a sufficient result without
spoiling the grain.
For polychrome mosaic on a smooth ground with an inlay of split sheepskin
pasted on Canson paper, the method already described for working mosaic of
one colour is the best, but at the same time the directions which are
given below for placing the differently coloured skins side by side in
position should be followed.
POLYCHROME MOSAIC ON A MOROCCO GROUNDWORK
Morocco leather for inlaying is thinned with the paring-knife, but it
cannot be reduced to the excessive thinness of split sheepskin. It
possesses, however, the advantage that the extreme edges may be made
thinner in proportion for laying one over the other at the point where
they meet.
After it is pared, the back of the leather is pasted over and it is pinned
out on a board to dry. The different parts of the design to be inlaid are
then traced on the various coloured leathers, and cut out in the manner
already explained. The difficulty of placing the pieces exactly edge to
edge is so great that it is better to allow them to overlap very slightly,
but in order that this should not produce undue thickness at the point
where they join, the substance of the extreme edges must be further
reduced with the paring-knife. A small margin is left for this purpose in
cutting out. Paring the edges to their thinnest possible substance will
give a slightly jagged outline, and the extra piece will thus more easily
merge into the join than if sharply cut. Outlining with the hot tool will
perfect the join.
PASTING THE INLAY ON A MOROCCO GROUNDWORK
To avoid crushing the grain of rough morocco, the tool illustrated in Fig.
33 is used instead of the roller to secure the adhesion of the inlay to
the groundwork, in order that the pressure may be applied only upon the
inlay. Damping the groundwork, except where the ornament is placed, should
be avoided. The tool is held pressed down with both hands as in Fig. 34,
and rubbed backwards and forwards. The work is then placed under boards.
MOSAIC ON MODELLED LEATHER
The remarks on paring leather for polychrome mosaic apply also to paring
the leather for covering a design in relief. An extra margin is left round
the edges, which are “slashed” with the tool, so that they may better
embrace the form of the modelling, the finer details of which are not
worked until afterwards. The leather is first placed dry in position over
the modelling, and smoothed over with a modeller, so that it takes the
form of the relief. It will then be seen how much should be cut from the
edges, so that it may exactly fit into the outline when it is pasted on.
INSERTED MOSAIC
This method of mosaic invented by Mons. Aumaître possesses the advantage
of being very durable, owing to the edges of the inlay being secured
between the two edges of the incision made in the groundwork. The outline
is deeply cut in the groundwork, the incision well opened with the opener
and then filled with paste. The inlay is also pasted and the edges
inserted in the incision. A wheel or a large modeller is used to press
down the edges, and the outline is then gone over with a hot tool.
[Illustration: FIG. 33, FIG. 34.——STICKING INLAY ON MOROCCO GROUND WITH
TOOL (FIG. 33) INSTEAD OF ROLLER, TO AVOID CRUSHING THE GRAIN]
[Illustration: 12. SHIELD OF CUT AND EMBOSSED LEATHER, _CUIR BOUILLI_.
ITALIAN, 16TH CENTURY.]
MOSAIC IN RELIEF
The term mosaic is perhaps not very correctly applied to this style of
decoration, in which the shape of the design is indented, by pressure, on
the damp surface of the groundwork, and filled in with an inlay of
leathers thick enough to stand out in relief, and be subsequently carved.
A thin kind of cowhide[8] specially prepared for embossed work is used.
The design is traced upon it in the manner described for carved leather,
and a preliminary modelling is executed indicating the outlines and
veinings as strongly as possible. The high reliefs may be embossed and
lightly stuffed. This done, it is placed upon Bristol board, not less than
half the thickness of the leather itself, with a piece of red transfer
paper face downwards in between. The whole is firmly fixed upon a drawing
board so that nothing can get displaced, and the design is cut out with a
stencil-cutter’s knife (Fig. 22). If possible, both leather and Bristol
board should be cut through at the same time, but should the knife not
penetrate the latter sufficiently to cut it through, the outline will have
been marked on it by the transfer paper and it may be cut out separately.
The leather and the board must, however, be absolutely identical in shape
and very sharply cut. With the die thus formed by the Bristol board, the
morocco groundwork is depressed to receive the inlay. It is thoroughly
wetted and the water allowed to sink in. The board is then placed in the
exact position which the leather inlay is to occupy, and covered with a
very thick sheet of blotting-paper to protect the grain of the groundwork
from being crushed too much. The whole is well pressed in the
copying-press until the die has sufficiently entered into the leather. The
leather inlay should then be tried in the hollow thus produced, and
trimmed where necessary if it be too large. After pasting it thoroughly,
taking care not to omit any small points, it is placed in position on the
groundwork and worked into the hollow with a modeller. The work is then
placed under boards to dry; a press would flatten the relief too much.
[8] Kip-skins.
When the paste is quite dry and the leather well stuck, the carving may be
proceeded with as described in Chapter II.
Very characteristic effects are obtained by colouring leather worked in
this manner.
INCRUSTED MOSAIC
The following description of a style of decoration, called by Mons.
Belleville “incrusted mosaic,”[9] is derived from the valuable work of
that author, entitled _Le Cuir dans la Décoration Moderne_.
[9] _Mosaïque par Incrustation._
In incrusted mosaic the design is not cut out and applied on the
background, but the different pieces of coloured leather forming the
design and the leather of the background are placed side by side on the
same plane. When the ornament is simple and the background plain, the
design is traced on the groundwork, carefully cut out, and used as a
pattern for cutting out the piece destined to replace it; when the
ornament is to embrace the whole surface, the following method is
recommended: The design, drawn on paper and coloured, is fixed on a
drawing-board and over it is placed a sheet of transparent paper, or some
thin muslin carefully sized and stretched. An exact tracing of the design
is made on rather stiff paper, which is coloured or numbered to correspond
with the pieces of the different leathers which are to compose the mosaic.
The tracing is then cut out, separated, and the pieces pasted on the
corresponding leather, either with the face on the flesh side of the
leather, or the back on its surface. In the latter case it is very lightly
done, but if pasted on the flesh side it should be done securely, as it
will remain permanently. When all these pieces are cut out of the leather
they are pasted in their respective places on the design, and the whole
put in the press for about ten hours. If the work has been well executed,
the lines where the pieces of leather come together will be hardly
visible; the next step is to accentuate them and make them regular. This
may be done either with a heated wheel giving a smooth even line, which
may, if desired, be subsequently gilded, or by pyrogravure. Vigour and
character can be imparted to the outline by the use of the latter process,
and the darkened colour of the burnt line is made more brilliant by
polishing it with an agate burnisher. In either case the tool must be
worked accurately with its edge half on each side of the line. The main
advantage of the process of incrusted mosaic is that the grain of the
leather employed is better displayed than in inlaid mosaic. It is only
suitable for work on a large scale.