9 Silversmithing

The silversmithing operations are often carried out in copper and gilding metal owing to the high price of silver.

The operations are the same and when sufficient skill has been gained using base metals the student can at a later date try working in silver. It is customary to have silver articles hall marked, but it is not compulsory if they are not to be sold. Hallmarking is carried out at the Goldsmith's Hall in London or in Sheffield, Birmingham, Edinburgh or Glasgow.

MATERIALS

Copper

This is a little easier to work than silver, but unless it can be finally workhardened by planishing it remains soft after the heat required for silver soldering.

Gilding Metal

Gilding metal is really a kind of brass having a composition of between 95% copper and 5% zinc, and 80% copper and 20% zinc. It is known as gilding metal because of its golden colour. Its working properties are very much like those of silver. It does not become too soft after soldering, and for this reason gilding metal is most used for the silversmithing operations in a budget.

Nickel Silver

This resembles silver in colour but it is harder to work. It can however be used on work which does not require a lot of forming.

CLEANLINESS

It is essential that all the tools and materials be spotlessly clean. Any speck of dirt, such as a metal filing, if left either on the tools or the sheet of metal will damage the surface of the metal if hammered. A slight burr on a hammer or a stake will also make nasty marks on the work and these are difficult to remove. Therefore all stakes and hammers should be kept polished and lightly oiled when not in use.

STAKES AND HAMMERS

The silversmith's most important tools are his stakes and hammers. Often special stakes have to be made to suit a particular job. These are sometimes forged from mild steel or they can be cast in iron from a wooden pattern. The bought stakes are often made of cast iron but some are made of steel. The working surface of a stake should be true and well polished. The raising stake and raising hammer are shown in figure 1, also the bossing mallet. The cylindrical mallet which is so often used for truing and removing dents etc. is shown in figure 3. The head is made from boxwood or lignum vitae and the handle is of cane.

Figure 2 shows some of the more common stakes. The treblet is used for truing rings and large conical work. It stands on the bench and is often about two feet tall. Mushroom stakes are mostly used for planishing. The two arm stake can be used for raising or planishing. The bottoming stakes can be used for truing the bases of canisters and boxes. The horse and crank are very useful because they can hold a wide variety of stake heads.

The three arm mandrel is used in much the same way as the treblet but for work on a smaller scale. The large tray hammer has oval faces of two different sizes for sinking and smoothing curves. The ball head hammer can be used for planishing inside curves of such things as ash trays. The tray setting hammer weighs about 2 1/2 lbs and is used for flattening large trays.

PROCESSES

Hollowing

This is the process used when making bowl shapes. It can be done with a bossing mallet using a hollowing block or a leather sandbag. Hollowing blocks can be made from beech or similar hard wood with the hollow on the end grain as shown in figure 1, or they can be made by gouging out hollows in the end grain of a tree stump which can stand on the floor.

To make a simple bowl shape first cut out a circle of metal with snips. Usually 20 or 18 SWG is used, but on larger diameters 16SWG is more suitable. The roughness is taken off the edges by filing (fig. 1) and the disc is softened by heating to dull red and quenching in water or dilute sulphuric acid, which is usually kept in an earthenwarejiough under a sink or near a water tap. This dilute sulphuric acid is known as 'pickle'. It is made by adding approximately 1 part acid to 9 parts water.

Remember always add the acid to the water not the water to the acid otherwise it splutters and can be dangerous. If the disc has been plunged in water it will be soft but the oxides will still be ori the surface and they must be removed by rubbing with pumice powder on a rag. If the disc has been plunged in the pickle it will be free of oxides but should be rinsed in water to remove any trace of acid and dried.

When starting to hollow keep the centre mark from which the circle is scribed on the convex side. The centre for the other side should be found with a pencil compass and concentric circles drawn at about 1/2" intervals. Now place the disc over the hollowing block or leather sandbag and with the pencilled lines uppermost gently tap with the bossing mallet slowly rotating the work and keeping the blows in concentric circles (fig. 1). It is usually better to start with the outside circle and slowly work inwards. If the work becomes too hard it should be softened from time to time as required.

The diameter of the disc will alter very little and the edge will remain at the same thickness; but where the metal has been stretched into the hollow it will have become thinner. If we wish to retain the thickness of the metal and make a deeper vessel we do it by raising.

Sinking

This is similar to hollowing except that a flat rim is left on the work as on a small tray. Often a blocking hammer is used instead of a mallet.

One method is shown in figure 1. The edge of the disc is kept against the pins (1/8 " diameter steel is suitable for these) and the work is slowly rotated as it is being hammered. After each time round it should be inverted on a flatting plate and the rim trued using a block of wood and a hammer. The bottom can also be kept flat by this method.

Note. Flatting plates may be bought. Actually they are nothing more than a sturdy surface plate. For school work an old surface plate can be used, but it should be painted round the edge with a distinctive colour so that it will not be confused with the surface plates used for marking out.

Raising

This is the process of making a hollow vessel by hammering or malleting from the outside.

The disc is best prepared from 20 SWG sheet. Only slight hollowing is required, about 1" deep on a 7" diameter disc.

Now a raising stake and raising hammer or mallet must be used. The raising hammer is the more suitable tool because a mallet, owing to its softhess, needs continual re-shaping at the face. This means that a new mallet will be required from time to time.

The raising hammer is shown in figure 1. It is important that the shape is as shown. Most raising hammers when bought need filing or grinding to the proper shape.

The stake can be made from 2" diameter mild steel about 16" long and held in a sturdy vice or a bought cast iron stake can be used. Ideally the bought stake should be held in a heavy stake block, but it may be held in a heavy vice.

Before starting to raise you should have a sketch of the vessel you intend to make. The size of the blank can be estimated by adding the average diameter of the vessel to the height. This will give you the approximate diameter of the blank. Experi­ence is needed to estimate the blank accurately, particularly since some people tend to stretch the metal more in hammering than others.

Start by making the base circle with a pair of dividers. It is better to have this circle scribed with dividers because a more precise base can be obtained in this way. Now make concentric circles with a pair of compasses on the outside of the work about 5/16 " apart starting from the scribed circle. These are guide lines for raising.

Place the disc over the stake as shown so that the scribed circle is just over the edge of the stake (fig. 1). Start hammering. Be sure that the face of the hammer makes a flat mark on the work. The hammer must bring the metal down to the stake but don't hit too hard otherwise stretching will result. Usually about three blows are necessary before the metal is properly down to the stake. The work is then turned about 1/2" and the next flat made. Continue until you have completed the first circle, then start on the next one 5/16 " up.

When this is done go on to the next and so on until you reach the last one. At this last circle the metal is usually wrinkled. It is better to tap these wrinkles hard down on to the stake using a cylindrical mallet. If a hammer is used stretching might occur at the edge. The diameter of the disc is now about 1/4 " smaller than before. Now soften, rinse and dry the work. Draw the concentric circles with the pair of compasses. The scribed circle should still show. Continue as before. The work will need softening at the end of each raising.

From time to time check the work to see that the sides are going up evenly. For this a cardboard template may be used (fig. 3). The work can be trued with the raising hammer on the stake but, instead of working right round, the raising is kept in short rows on the side which is protruding. Figure 3 shows how the shape alters with raising. Figure 4 shows a teapot which has been raised.

Often to save time tall vessels like coffee pots and vases are first developed and seamed using hard solder (the enamelling grade is too hard) and then finished by raising (fig. 3).

When raised work has reached the desired shape it can be planished to remove the raising hammer marks.

Planishing

This is the process of making the work "plain", but in fact the planishing hammer leaves small facets on the work which can be attractive if done regularly.

Before starting to planish, be sure the stake is highly polished, also the work and the hammer.
On hollow work the stake must have a slightly smaller radius than the work so that when the hammer strikes the work it istrapped between the stake and the hammer (fig. 3 (1)) and makes a clear ringing sound. Often a different stake and ham­mer are needed for different parts of the job. A simple bowl as shown in figure 3(1) could be done using one stake.

Before starting to planish work similar to figure 3(1) draw concentric circles about 1/8 " apart and start planishing from the centre. If the work and the hammer are polished it is difficult to see the hammer marks, but this can be overcome by rubbing the hammer backwards and forwards on a piece of 3/0 blue back emery paper. This gives the hammer a very fine satin­like surface which shows as a fine matt surface on each of the facets. When the planishing is finished this slightly matt surface is easily polished using crocus or rouge block on a soft mop such as a "swansdown".

Each facet in planishing should overlap the previous facet and each row should overlap the previous row. After planishing the work is hard. Sometimes to remove the raising marks the job has to be planished two or three times.

Some planishing has to be done with a collet hammer (fig. 3 (2)) or a blocking hammer (fig. 3 (3)). A 10 oz planishing hammer is shown (fig. 3(1)) but for small work a 5 oz hammer can be used.

Planishing does three things:
1. It makes the work hard.
2. It spreads the metal slightly.
3. It makes the metal a little thinner.

Snarling

This is the process of striking a blow (usually on the inside of a container) by utilising the rebound of a long slender tool, one end of which is gripped in a vice (fig. 5). By this means it is possible to alter the shape or remove the dents from deep awkward shaped vessels.

Caulking

Caulking is a method of thickening the edge of a piece of work by hammering as shown in figure 5. It is done for strength and appearance.

Start by slightly chamfering the edge as at figure 5(1). Then hammer round and round three or four times, keeping the blows close together, until a thick edge is obtained as at figure 5 (2). The hammer marks and any burrs can be removed with a water of Ayr stone. Water of Ayr stones have a mild abrasive quality. They are available in sticks about 3 1/2 " long ranging in size from 1/8 " square section to 1 " square section. They are used with water.

Built Up Work

Often a hallowed or raised bowl requires a base or foot. One of the simplest kinds is shown in figure 6A. The base ring is made first and the joint soldered with hard or enamelling solder. Notice the little spacing pieces of iron wire to prevent the solder from running on to the binding wire; also the extra loops for tightening the wire.

The ring is next soldered on to the body using easy or easy-flo solder. To be sure the base ring is properly positioned it is a good plan to make stitches with an engraving tool as shown at B. This ensures that the base will not move during soldering. Be sure to keep the graver sharp or it will tend to slip. Engraving tools are discussed in Chapter 10.

Wires can be applied on rims or on bases. These can be held in place with bent cotter pins as shown at C.

Boxes and Seamed Work

Figure 6D shows the method of using iron binding wire on several seamed jobs. The clips shown are made from 20 SWG annealed mild steel. These are particularly useful for large work on which the edges tend to come out of alignment on heating.

When finally soldering the cover on a box, air vents must be made, as shown, usually by starting to saw at the joint line of the box and the cover.

When soldering the bottom on to a box it must be lifted from the firebrick slightly to allow the flame to heat the bottom. The circular box is shown on cotter pins and the rectangular box on 1/8 " diameter iron wire.

Rectangular boxes are developed from a flat sheet and "V" grooves are made where the sharp bends are required.

"V" grooves are usually made with a scoring tool (fig. 7). This can be made from silver steel which is then hardened and tempered to light straw. The edge should have an angle of 90° for rectangular boxes, 60° for hexagonal and 45° for octagonal shapes. A piece of metal is clamped beside the line to be scored to act as a guide. The score should be made so deep that when the metal is turned over it shows as a slightly raised line. If the scoring is not deep enough, the bend will not be sharp. Care must be taken, however, not to score right through the metal.

Scoring can be done with a properly ground cold chisel or a file, but the filing method is only to be recommended when the grooves are short.

After the box is folded it is usual to silver solder along all the folded joints. The base can be mitred as shown at B, or soldered flat on to the sides (A). When the top has been soldered on and the box finally sawn through with a piercing saw, the sawn edges must be filed flat and tested on a surface plate. The inside edges of the box are finished with a bezel. This helps to locate the cover and gives the box rigidity. The bezel is soldered to the box with a lower melting point solder than is used for the rest of the joints.

Wire Drawing

Often wires are required to strengthen the edges of bowls or for bezels in boxes.

Wire can be altered in section and reduced in diameter by being pulled through a drawplate.

Drawplates are available with round, square, oblong and triangular holes. They are made from hardened and tempered steel.

Figure 8 shows a drawplate. The holes progress in size from one end to the other. Each hole is tapered. The wire to be drawn is first softened and the end is tapered with a file as shown. The tapered end is inserted in the largest hole throughwhich the untapered part of the wire just cannot pass. The drawplate is held in a vice and the wire is oiled or rubbed with beeswax or soap and then the tapered end which is protruding through the hole is gripped with the tongs and pulled through. It is then drawn through the next hole.

Drawing causes work hardening so the wire must be softened often. To do this, coil it up so all the coils are touching each other, otherwise stray coils will become burnt before the others have reached the annealing temperature. Clean and lubricate the wire before continuing with the drawing. With care two wires can be drawn through the plate together as shown.