CHAPTER XIII 
REPOUSSE WORK  Materials and tools—Pitch—Lead or zinc—Board work—Composition of pitch—Removing pitch—Repouss6 and chasing tools—Sna,rling irons. 

Repousse is a general term to describe ornamental work produced by modelling sheet metal with hammer and punches. It differs from cast ornament and from stamped Avork both in design and in treatment. For upon the visible traces of its method of production a considerable portion of the charm of repousse work depends. The thoughts which the craftsman was able to put into his work supply the remainder. The surface of the work should be bent to and fro to catch the light at different angles. Some parts of the ornament should be lower in relief than the rest, and should fade aAvay into the background. The thing to avoid in this and all other relief work, is the effect of ornament Avhich has been made from a different piece of metal and has been stuck on to the background. It should be obviously of one piece, but with surfaces tilted about to play Avith the light, an ornamentation of the metal rather than a decora tion applied to it. Strictly speaking repousse is that part of the work Avhich is done from the reverse side of the metal —the bossing up of lines or patterns from the back. Chasing is the part which is done from the front. The term chasing is also applied to the touching up of cast work. 

When a raised pattern is to be produced on the surface of the work, the metal is placed face downward on a pad of some material which will yield sufficiently to the force of the blows given, but which will at the same time support the metal near by, and prevent it from being disturbed. For this purpose it is necessary that the supporting material shall be in continuous contact with the underside (really the face) of the work. Now the best material for this purpose is pitch, prepared as described below. Pitch being an adhesive material, too much so sometimes, it will remain in contact with the metal, even after a considerable amount of hammering; and owing to the even support given to the metal a sharp impression will be made of the shape of any tool used, especially if the pitch is allowed to get cool and hard. A tool, however, is generally moved about while being struck by the hammer, so that an impression of its exact shape is rarely visible. 

To obtain any considerable amount of relief it is neces sary to work while the pitch is warm and soft. It sets fairly rapidly. A support of lead, tin or zinc, Avill give a clear, sharp impression, and these materials have the ad vantage of being clean to work Avith. Not, however, being of an adhesive nature, they do not keep in close contact Avith the work. So, after a small amount of hammering, some parts of the metal will be found to be unsupported, and therefore unsafe to Avork upon. A cake of one of these metals is most valuable as a backing Avhere a small amount of bossing up is required, as in knocking up little discs or leaves. Care must, however, be taken to remove any particles of zinc or tin or lead, which may have transferred themselves to the AArork, for they would cause serious damage if it had to be heated aftenvards. Linoleum and Avood are two other materials which can be used as a backing, but pitch is the best all-round material. 

Patterns in relief can be, and often are, obtained by beating down the background of the design from the front, instead of by raising the ornament above the level of the background by working on the underside of the metal. 

Among the various ways of holding the metal the simplest is that of fastening it to a board with nails. This method is only suitable when outline work, or very low relief is required, as on a tea-tray. It has the advantage, which pitch has not, of being quite clean to use. The best nails are 1-inch oval sprigs. They are driven into the wood, at intervals of 2 to 3 inches, all round the sheet of metal to be worked upon. The nails are not placed close up to the edge of the metal, but about 1/4  inch beyond it. They are driven about 5/8 inch into the wood, the remaining portion is then knocked over sideAvays on to the metal. The nails, being oval in section, bend easily, but care should be taken that their heads are not liammered into the metal, for the little marks they make are difficult to get rid of. In tracing a large piece of work, the central parts should be done first. When the work has proceeded for a while it will be found that, owing to the stretching of the metal, parts of it have risen from the board. These must be tapped down till the metal again rests on the wood, it being almost impossible to work on the metal where it is not firmly supported. It will be found that the most convenient tools for this purpose are a mallet or a levelling tool—a piece of boxwood 3/4inch •-•• square by 4 inches long, used as a repousse tool. In this and in nearly every other case where tools are used to drive sheet metal flat, the section of the tool, where it touches the metal, should be flat with rounded edges and corners, Fig. 198. The reason for this rule is, that when the force of the blow carries forward that part of the metal with which it comes in contact—disturbing the adjacent metal very little—a square-edged tool would leave a sharply defined mark, or cut, round its outline. The tool with rounded edges, however, would bend the metal there without cutting it. 

When the outlining is completed the work can be back grounded, if necessary, where it is. In this part of the work it is well to commence near the traced lines and Avork towards the more open parts of the background, and not from the middle of the open spaces toAvards the pattern. For by working in the last-named direction a little hill of metal will be driven up near the traced line and this will be difficult to get rid of. Backgrounding is done Avith levelling or matt tools, and the hammering thus given to the background drives the pattern up in relief. The amount of relief produced in this way varies with the thickness of the metal. For a tray about 20 inches by 9, copper size 10 on the metal gauge should be used, and the relief would be about 1/16 inch. For a tray 24 inches across, size 12, the relief would be rather less. Size 15 is too thick for it to be possible to produce much relief by this method. By the time that the backgrounding is completed, the whole work Avill be found to have stretched, perhaps -J inch to the foot. Hence the necessity of placing the nails in the first instance at some distance from the edge of the metal. Woods with a strong grain, such as oak, pitch-pine, etc., are not suit able for repousse boards, as after some use the harder part of the grain of the wood is left standing in ridges. 


Among the tools required for repousse work will be— 
1. A board of some hard, close-grained wood, such as sycamore, measuring say, 20 by 12 by 1 inch, for use as above described. 

As a ground, pitch allows of far greater possibilities in the way of relief and texture than other materials do. The pitch used is that known as Stockholm, or Swedish, pitch. It is dark-brown in colour, and can be obtained from any dealer in jewellers' requisites. Pitch is too brittle to use alone, it must be mixed with some other substance to make it tougher. For this purpose tallow and plaster of Paris, mason's dust, bathbrick dust or resin, may be used. 


Take— 
(i) Pitch 10 lb. 
Brickdust 20 „ 
Resin 4 „ 
Tallow 2 „ 

(ii) Pitch 6 parts,
Brickdust 8 „ 
Resin 1 part, 
Linseed oil 

or— 

(iii) Pitch 14 lb. 
Resin 14 „ 
Plaster of Paris or brickdust 7 ,, 
Tallow 8oz 

Melt the pitch, or the pitch and resin in an iron pan. When quite liquid add the plaster of Paris or brickdust by handfuls, stirring well all the while. Put in the tallow last. Its effect is to soften the composition, so rather more tallow may be required in cold than in warm weather. Linseed oil is sometimes used instead. 

2. A pitch board. This is a rough wooden tray 1 inch deep, filled with pitch. It should be made as large as you are ever likely to require. To fasten a piece of work upon it, warm the surface of the pitch with a bloAvpipe, taking care not to set it alight. For that would be dangerous, and the cinders of burnt pitch act as air-bubbles, so you do not get an even support for the metal. With blowpipe and a rod or spatula level the surface sufficiently, removing any burnt pieces. Then lay the metal upon the pitch and press it down with the handle of a hammer. Place weights on it until it has set. Should any bubbles be left under the metal, they can be located by the hollow sound which the metal over them will give when tapped. Heat any such place with the blowpipe, or by placing a piece of red-hot iron on it, and press down again. 

To remove the work from pitch. If the pitch is quite hard a repousse tool driven under the edge of the metal, between it and the pitch, will often give sufficient leverage to crack the metal off. But if the pitch still holds, or there is any danger of injury to the work, it is safer to Avarm the metal with the blowpipe. The heat melts the pitch in contact with it, and will allow the work to be lifted off with pliers. The metal is then made a little hotter, though not hot enough to set the pitch alight, but just enough to induce the pitch still adhering to it to flow easily. The work can now be wiped clean with cotton waste or a brush dipped in paraffin. Paraffin readily dissolves partially melted pitch. But should the pitch get chilled before it can be all removed from the metal, it may be necessary to warm the latter again. Care must be taken in this case not to set everything alight. Burnt pitch is difficult to remove, 
Indeed, the simplest way to get rid of it is to anneal the work thoroughly and plunge it into water. It may be necessary to do this twice to remove all traces of the burnt matter. Molten pitch is very sticky, but it can be handled with impunity, when it is not too hot, if the hands are kept wet. 

3. A pitch boAvl and ring, Fig. 199. The boAvl is hemi spherical, of cast-iron, 9 inches in diameter and about \ inch thick. Filled Avith pitch it weighsabout 20 lb. The weight is of importance, for if the bowl is much lighter it Avill be likely to dance about when you Avork on it. It stands on a ring, Avhich may be of leather or of coiled rope. The bowl can be turned about or tilted to any angle as the Avork proceeds, all the Avhile standing firmly in its ring. 

4. Two hammers. One weighing about 16 oz., this may be of almost any shape if it has a flat face. It is used with the larger repousse tools. A light hammer is unsuited for such work. The second hammer is the chasing hammer shown in Fig. 200. The head weighs 3 or 4 oz., and the handle is about 9 inches long. Its rounded end makes it easy to hold, and use. A wooden mallet can be used instead and it makes less noise. 

5. Punches and chasing tools of various shapes. Although a considerable amount of ornamental work could be done with a couple of punches—a tracer and a backgrounding tool—yet one would soon find their limitations. Fifty to seventy repousse and chasing tools make a useful set, though a professional worker may have several thousand. Out of these he has perhaps a dozen favourites. The tools are all about 4 inches long, but they vary in thickness. The smaller ones are generally forged thicker in the middle of their length, as they are then easier to hold. Tools with sharp angles or rings on the shank hurt the fingers, so they should be avoided. It is better and cheaper for the worker to shape the points of his tools as he may need them; for the tools he can buy are rarely the exact shape that he re quires, Unfinished tools, called blanks, can be bought ready forged. They only require the points to be shaped and hardened, and are then ready for use. The tools being all very much alike except at the point, the description given below refers to that part of them which actually touches the work. Although no two in a set are alike, the tools fall naturally into a few groups, known by the following names. Tracers. Bossing, cushion, modelling and chasing tools. Matts, freezers and liners. Ring, number and letter-punches. 

Tracers are like rather blunt chisels, and are used chiefly for outlining. Their working edges vary from about 1/100 inch in thickness by 1/16 inch long, to perhaps 1/8 inch wide by 3/4 inch long, Figs. 201 to 204. The last one is curved as shown in the section. A very useful size is about 1/04  inch thick by 1/8 inch long. 

Tracers and all the other tools are held in the same way— between the thumb and the first two fingers of the left hand. The third, and sometimes the fourth, fingers rest on the work to steady the hand, Fig. 215. The tracer is held nearly perpendicularly, but leaning back a little from the direction in which it is to travel. The front corner is thus lifted a little above the metal. If a blow is now struck with the hammerontheupperendofthetool,the corner of the tracer, known as the heel, will be driven into the metal. The tool will, at the same time, move forward slightly. The blow is repeated again and again, the edge of the tool slowly sliding forward and cutting itself a channel in the metal. Some of the material displaced goes to form a little ridge on either side of the traced line. Some of it, if the metal be not too thick, is driven up in a ridge on the underside of the metal. Some difficulty may be found at first in getting a tracer to work properly. If held too nearly perpendicular it will not move along at all, but will dig into, and perhaps cut through, the metal. If held at too great a slope, the point will slide away, making merely a scratch on the surface. The correct angle to hold it can be ascertained only by trial, and it varies with different tracers. In making curves of small radius it is necessary to tilt the tracer back further than usual, so that only the heel touches the metal; for if held at the usual angle, it would be likely to make a series of tangential marks round the outside of the curve. The tracer is much more likely to slip away when so held, so it must be gripped very firmly. Curved tracers, Fig. 204, are sometimes used, but with a little practice curves of anyradiuscanbe,andgenerallyare, workedwithastraight tracer. At whatever angle the tracer may be held to the metal, the blow from the hammer should always fall in a direct line with the axis of the tool. Beginners frequently make the mistake of striking the head of the tool at an angle instead of fairly on the top—with surprising results. If the point of the tracer is dipped occasionally in oil it will move more freely. The edge of the tracer which is to touch the work is not invariably made just at right angles to the shank of the tool, as in the case of an ordinary chisel. It may be sloped like a skew chisel, and vary as much as 20° from a right angle, Fig. 203. If made so, it will travel easier. The heel of the tracer is sometimes rounded off a little. The bottom of the groove made in the metal should not show " stitches," it should be nearly smooth. 

Bossing and cushion tools, Figs. 209 to 214, are made in various shapes :—round, tapering, square or oblong, but they are all alike in this—their sharp edges are rounded off. For the purpose of this group of tools is to drive the metal up in bumps or ridges, and any sharp corners on the tool would be likely to cut or tear the work. Bossing and cushion tools are therefore more or less circular in section at their working ends. Modelling and chasing tools, Figs. 205 to 208, on the other hand, being used on the front surface of the work, are, as a rule, much flatter. Many of them are quite flat at the point, though sometimes the extreme edges are rounded off. It will be clear, how ever, that to obtain a rounded or a level surface on the work, one would hardly care to use a very rounded tool. It is on this very point that so many ready-made tools fail, they are not flat enough. The ideal tool is quite flat in the centre, though it may, perhaps, have its corners and edges rounded off a little, as in Fig. 198. 

Lining, freezing and matting tools are used to give variety of texture to the work. Liners have a number of shallow lines, or grooves, across them; the others are hatched in different manners. The function of this whole group of tools has been much abused. Texture is often relied upon to produce changes of light and shade which should have been caused by changes of plane. It is better to produce the desired effect by modelling the surface than by altering its texture. These tools are useful in touching up cast work. A very finely grained matt tool can be made by nicking a rod of hard steel all round, then breaking a piece off and using the broken end. 

Ring tools make a circular mark, as their name implies. Number and letter punches are made in sets. The letters or figures are reversed, like type, if they are to be used on the surface of the work; but are not reversed when the punches are to be used on the underside. 

Tools for backgrounding or for producing an " all over " texture are so held that they can be moved about freely just above the surface of the metal, the force of the hammer blows bringing them into contact. The work can be done thus much quicker than if the tool is brought to rest upon the surface of the metal, and the blow then given. 

6. One or two snarling irons, Figs. 219, 220. These are rods of iron perhaps a foot long by about 1/2 inch square. One extremity is held in the vice, and the other ends in a rounded knob set at right angles to the axis of the rod. These tools are often made Z-shape, as shown in Fig. 220. They are used to produce bumps or bosses on the outside of tubes, bowls or other vessels which are too narrow in the mouth to allow the insertion of a hammer, or repousse tool, for that purpose. One end of the tool being in the vice, the bowl or other work is so held that the knob on the tool is pressed firmly against the underside of the place where the boss is to be produced. A sharp blow is now giventothatpartofthe snarlingironwhich isnearthe vice. The rebound from the blow causes the knob to strike sharply against the metal opposite to it. The blow is repeated again and again, until a sufficiently large bump has been produced on the work. It may be necessary to anneal the work should it get hard before this result is attained. The pattern, having been roughly bossed up in this manner, can be finished from the front with chasing tools. An iron bar should be used to strike the snarling iron. It is easier to manage than a hammer. 

7. Two or three cakes of zinc, tin or lead, weighing 3 to 10 lb., for use as described above.