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07 31st, 2009| 
Metalwork in China Restoration
Now for the techniques involving metalwork and drilling. There are three main types of drill, the hand drill or Bob drill; the hand twist drill, or the power drill.
Bob Drill. The Bob drill, which is the traditional china restorers’ tool, consists of a steel spindle with a bob of wood towards the lower end, an eye at the top, and a tapered point at the bottom. It has a cross bar of wood with a hole in the middle which lets it slide up and down the spindle. A lace is passed through the eye at the top of die spindle and fastened to each end of the cross bar.
The cross bar is held by placing three fingers on top of it and the thumb and little finger below. Make a small starter hole in the china with a broken file or a diamond and place the point of the drill, which carries a tube containing a drilling diamond, in this hole. Keeping the drill upright, press down gently on the cross bar. This moves down the spindle, unwinding the lace and turning the spindle complete with bit. The impetus of the bob, acting as a kind of flywheel, carries the rotation of the spindle a little further as the pressure is relaxed and then back again rewinding the lace onto the spindle. Keep the drill straight, don’t let it sway from side to side, and lubricate the bit with oil as the work goes on.
Hand Twist Drill. This is used much the same way, although it is for sonic people not quite such an easy tool to use. It is necessary to exert a little pressure to get the bit to bite, and the piece must therefore be firmly held.
Power Drill. Provided your drill runs at about z000 r.p.m. it call be used for drilling, especially in substantial pieces. The hole will have to be started by hand. Special bits are needed, and the drill must be mounted vertically on a bench stand. For some jobs a horizontal stand will have to be used. If the piece is properly held under the drill, and you are not too heavy handed, this method should be satisfactory.
Tack some kind of pad to the workbench under the drill to act as a shock absorber. This should not be too soft; a piece of thick lino or cork will do.
Put the drilling tube into the chuck of the drill and start the motor, checking carefully to make sure that the tube when spinning is absolutely straight and not whipping at all.
Put the piece of china on the bench under tile drill and bring the machine down, not switched on, to within an inch of the working point. The hole should already have been started with a hand drill. Get everything perfectly aligned and secure the piece to the bench as best you can. Start the drill and bring it very very gently down into the hole. The moment it bites, lift it and have a look to see if you are working straight. Then lubricate with water (or turps if you are drilling glass) and continue drilling, lubricating frequently. To drill large holes, start by drilling a small one, then enlarge the mouth of the hole for the next size drilling tube with a tungsten carbide bit. This means a lot of bit changing, so don’t forget to check for whip each time.
To keep objects steady under the drill, prop them up with large chunks of plastid ne. Small objects can temporarily be set in plaster of Paris, in a small wooden box at the right angle for drilling. If your piece of china is so big that there isn’t room to get it under the drill, it may be possible to swing the drill round so that it points out over the side of the bench, and then the china can be put on a separate table at the right height.
All drilling takes a steady hand, a straight eye and a light touch. If die drill waves about the results won’t be very good, and if too much pressure is applied there is always a risk of splitting the china. This applies especially when using a mounted power drill, as you have so much leverage and it is harder to tell by feel just how much pressure you are putting on. Practice on some useless bits and pieces, for hours, if necessary!
Dowelling. Dowelling is die joining together of two pieces by boring a hole in each, the ends of which match exactly, so that either a straight pin, or a pin angled at the join (as in a knee joint) can be cemented in to hold the two together. For most purposes half hard brass wire 132, in a A’ diameter hole, is right. The holes should be about a quarter of an inch deep. To align the holes properly, bore one side, then push the tip of a thoroughly wet indelible pencil into the hole so that it is well ringed with ink. Then bring the other, undrilled side to the join tight against the drilled piece in exactly the right position. The indelible ink will mark the undrilled piece, and you can go ahead and bore right on the mark. Countersink one or both holes with a slightly bigger bit.
Take a piece of brass wire and flatten it slightly on one side to allow air to escape from the holes as it is inserted. Push it home into one of the holes and cut the wire, allowing sufficient length to go to the bottom of the other hole. Then fit the second piece over the wire. If the wire is too long to allow the faces to come together properly, snip off a little tiny bit and try again until you do get an exact fit. Obviously, the secret of this job is to be sure your holes are accurately bored facing each other, or you will spend ages fiddling about bending the wire or enlarging holes.
When die wire fits properly, take the wire right out and Jay it on the work bench and roll a rough file backwards and forwards across it so that it is scratched and scored to make a key for the cement.
Make up some cement (see Fillers and Cements) from whichever mixture you fancy. Araldite and titanium dioxide or kaolin or whiting are as good as any because Araldite sticks so strongly. Fill one of the holes, that on the bigger piece of china and push in the dowel making sure that it goes right home as it did when you fitted it. Sonic cement will ooze up into the countersinking. Wipe it away, as the countersinking will later fill with cement from the other side of the join and this will help to hold the two pieces together. Try the second piece over the dowel just to make sure that everything still fits. Then remove it, and leave the dowel to set hard in its cement. The next day, or after baking for half an hour at zoo deg F. if epoxy resin has been used, clean the surfaces of the break with methylated spirit, and make up some more cement and fill the hole in the second piece. Provided the broken edges of the piece fit perfectly it is not necessary to put adhesive between them. Adhesive will in effect widen the join a fraction and make a line which will show. But if there arc irregularities or missing chips, then put some adhesive or even a little filler composition in to fill them out. If you decide that adhesive is necessary, put a thus layer on one side of the break only.
Push the second piece well home on to the dowel, and make sure that the fit is good. Bind the pieces together with gummed strip as described before.
Dowelling is used to join modelled or moulded or cast pieces to the whole in exactly the same way. Dowels will also support joins in hollow china, or help to join hollow pieces to solid pieces. The solid piece is bored in the same way as before, but the reverse process has to be carried out in the hollow section, a block of cement being built up to hold the dowel. When both sides are hollow and the hole is large use a heavier gauge wire or make a dowel out of a tube of brass. It is difficult to fill in a large space with cement and to set a small pin iri the middle of it. Wrap a ribbon of cement composition round and round the dowel until it is enough to fill the cavity, and push the dowel, with its cement wrapping, firmly into place. The cement may ride up the dowel if it is too much to go into the cavity, and it will not adhere if it is too little. Having cemented in one end of the dowel, leave it to set, and then swathe the protruding end in die same way, finally fitting the broken piece over the dowel and cement, until a flush join is achieved.
pitillilig. In some ways, pinning is easier than dowelling. A hole is drilled through the broken sections after they have been stuck together and a pin, prepared in the same way as a dowel, is pushed into the hole which has been filled with a fairly liquid cement mixture. The advantages of this method are that there is no difficulty in getting the holes to match up as they are drilled in one go, and that no binding is necessary as the join has already been made. The pin is sunk well into the hole so that the outer end is just below the surface. The hole is then filled in with composition and overpainted in due course (see Fig. io).
Cores. Cores are commonly used when a large missing section has to be built up, to support a piece which may sag
these two pieces
cannot easily or be liable to breakage. Wire of a suitable gauge is used according to the thickness of the china. Holes are bored each side of the aperture, only just deep enough to accept the end of the wire. A piece of wire just slightly longer than the gap is cut and roughened, and sprung into the holes. Or a piece of wire is put into each hole and joined in the middle by soldering. Several pieces of wire can be put across a gap if necessary. If the part to be replaced is curved, a teapot handle for instance, a correctly shaped core of wire is set into holes at each end of the break (see Fig. to). Shaped cores can be made as skeleton frameworks for almost any shape or size of missing piece. Sometimes a core is not fixed at each end, but is a dowel set in the edge of a gap (see Fig. io). A bent pin makes a skeleton limb on which to build up a whole piece by modelling.
All these techniques can be combined with those described under the headings of Sticking, Moulding and Modelling.
If the china is thick enough to carry drill holes, and it is intended to make a press mould out of plasticine or Paribar, a core or cores can be put across the gap to strengthen the new piece, the filler composition being carefully tooled in to cover the wires.
Cores can be a great help when modelling. It is not possible to make a model direct by putting a large lump of composition over and round the core, it will just slip about the wire. First wind a ribbon of composition round and round the wire, and leave it to set hard. Then do the modelling on this conipo base.
Overpainting. The art of overpainting mends in china so that the repair becomes indistinguishable from the original is skilled indeed ! If you cannot paint anyway, then it is going to be pretty difficult for you. The work is done with good quality water colour paint brushes, and you will need several sizes, particularly some good fine ones. Artist’s oil paints are fine because they can be mixed so easily to make absolutely any colour. Reeves Artist’s Gel makes a good medium, or clear enamel glaze if you can get it. If you want the work to dry out quickly add drying agents bought from Artist’s Colourinen. Just how glazed the final result may be depends upon the medium, but the final result can always be varnished if it is not glossy enough. For work where opaque colours are needed, polymer paints are ideal and can be mixed with their own glaze mcdiLini to get a high finish. Darwi Italian Glaze is also excellent for work on china.
Many school teachers know about the modelling compound made by Darwi, and this firm now make a most excellent range of paints for their modelling compound which can be used on china to give the effect of glazes without firing. Darwi transparent paints are available in twelve colours, and thereis a similar range in opaque paints. Both types of paint when dry should be given a coat of the special Darwi Varnish, as this gives it the ceramic lustre, and dries hard to give lasting protection. They also make metallic paints called Darwi-Or and Darwi-Al in gold and aluminium.
The normal technique for building up colour to re- create glaze is to start by painting the whole area with a ground colour which exactly matches the ground colour of the original. This may be anything from black to white, but will probably be fairly opaque and will contain a lot of white. After this layer has dried, further layers of more transparent colour are built up over it until the decoration matches the original. To explain in detail this is done would be to embark on a course in oil painting. As a simple example, flesh colour is made up of at least five colours. White, a little grey or blue, black, yellow, and crimson. If you mix all these colours together in any proportions the result will be an opaque putty coloured paint. Applied in transparent layers very thinly, first wltite, and then the lightest touches of blue, grey and black, and then a little yellow and a final coat of transparent palest crimson, it will build tip beautiful flesh tones. The portrait painter teams all about this, and if you are going to do much of this kind of work a good book on oil painting techniques could be lielpfiil.
Perhaps I have made ovcrpainting sound too difficult—but it isn’t really, and it is great fun, and astonishingly good results follow just a little practice.
Here is a list of colours which will cover any range you want and will come in useful for other restoration jobs. You might even get interested in painting in oils, if you aren’t already. Anyone who has an oil paint box will have enough colours and will know enough about painting to go ahead without further purchases except medium. Dry powder pigments in several of the tints below are also very useful for all kinds of restoration work. It isn’t necessary to have all these colours. For small jobs just buy the ones you need and so build up a stock piecemeal. Polyurethane glaze gives a good hard clear finish if a high gloss is required.
Colours. These should be oil colours.
Titanium White Ivory Black Cobalt
Naples Yellow Yellow Ochre Burnt Sienna Burnt Umber Rose Madder Indian Red
Deep Cobalt Green Chrome Green
Artist’s oil and riot Student’s
Paynes Grey
French Ultramarine Cerulean
Winsor Lemon Raw Sienna
Raw Umber Venetian Red Cadmium Red Viridian
Permanent Green
GLASSWARE
Wash glass with liquid detergent in warm water, and brush cut glass gently with a soft brush. Dry it and polish it with a silver cloth. If badly stained cut glass is left to soak overnight in warm water and detergent with a few drops of ammonia added, the dirt will probably come off. Tile cloudy deposit left oil glass by lime in water is the devil to shift. Fill the glass with distilled or rain water, rim tap water, and leave it for a day or two and then scrub gently. If the lime still persists a little spirits of salt may shift it. Spirits of salt is a pretty good shifter of all kinds of stains, and it also makes neat little shot holes in your clothes if you spray it when
brushing!
Bad stains will usually yield to a soaking in a five per cent solution of caustic soda. Metal polish will remove stains on glass. Decanters and bottles with stains which will not yieldto brushing or which cannot be reached can be cleaned with said, preferably silver sand. Put in a small handful of sand, some detergent and a little warm water, enough to allow the sand to swirl around when the bottle is shaken. A careful swirl or two should abrade off the stain. A five per cent solution of nitric acid will clean off wine stains.
Scratches oil glass will sometimes respond to a good Polish with jeweller’s rouge. Glass is a strange substance which does in fact flow, and rubbing with rouge does actually make it flow and fill in the scratches.
Removing Stoppers. Glass stoppers sometimes get firmly stuck in old decanters and glass bottles, and brute force is the worst possible way to shift them. Make up a mixture as follows:
2 parts alcohol
I part glycerine
i part common salt
Paint this oil the stopper, particularly where it enters the bottle or decanter, and leave it for a day. A few gentle taps should then shift it. If this doesn’t work, heat the decanter over a stove, or stand it on a radiator so that the air inside will expand, and force out the stopper. This method will have to be used if a stopper has broken offshort in the neck of a bottle. Keep the piece that comes out for it may be possible to repair it.
Making Lamps out of Bottles. Large glass jars and carboys can be made into lamp stands and this job always looks best-if the jar is to be filled with solid or semi-solid matter such as pebbles, or sand—if the flex passes up through the bottle. If the jar is to be filled with liquid, obviously there are difficulties in preventing leakage through the flex-hole, and in keeping the flex totally insulated from the liquid. Outside fittings are best and safest for liquid filled jars.
Bore holes in glass jars exactly as they are bored in china. The safest way is to start by boring a A” hole with a diamond drill, lubricating constantly with turpentine. Then enlarge the hole with successively bigger drills until it measures which is big enough to take the flex. Start each bigger hole for the follow-up drills with a tungsten carbide bit, and don’t push through too fast or the
will drill
glass wi split. just let the grind gently away. A little practice on a spare milk bottle is advisable if you haven’t done the job before.
Mending Glass
Sticking. On the whole glass is stuck together in the same way as is china. There are one or two small points of differ- ence. The edges of broken glass are very smooth and some roughing up with a diamond scratcher will give the adhesive a better key. Gum strip is used to put tension across the joins as described in the section on sticking china. This is very important when mending glass as a very tight fit is essential to ensure adhesion. When the adhesive leas set, surplus which has squeezed out is removed by rubbing it down with steel wool, not glass paper as this would scratch the glass. Remaining adhesive can be lifted off with a scalpel or a razor blade.
Wine glasses so often break across the stem, and such breaks can be mended with Araldite, but won’t be particularly strong because glass tends to break again near the point of the first break even if the join itself holds firm. Stainless steel bands are sometimes put round stein-breaks, but this is an expert job and the band must be very accurately made so that it can be sprung over the stein and glued tight round the join.
Dowelling. Dowel glass as you dowel china. This is a better method of mending a wine glass stem. The dowel will show, but inside the stein the Aralditc/titan dioxide cement looks rather like frosting and is not unsightly. Glass is more fragile and shatters more easily than china, so take just that much more care when drilling.
Glass that has been mended with epoxy resin can be heated to speed up setting, but remember that glass breaks if exposed to sudden changes of temperature. Therefore it must be put into a cold oven and the heat brought up gradually to about i 5o deg. F. Then switch off the heat and without opening the oven door leave it to cool right off again. The draught caused by opening the door would crack the glass. After an hour the oven should be cool enough and the adhesive set. Only white clear glass may be heated; coloured glass cannot be stoved and the adhesive will have to be left to harden in its own sweet time.
Moulded Repairs. Glass can be repaired with liquid acrylic resin, of which there are several makes on the market. Technovit 4004A dries to a clear glass-like material. It can be polished and it can be coloured. Acrulite and Tensol Acrylic are two other very good materials for this work.
Make plasticise moulds as described in the china section, but always use white plasticise as acrylic will take up colour from coloured plasticise. No parting agent is needed unless the makers of the acrylic so state. Technovit is made up by adding hardening liquid to a powder, and it is then poured direct into the mould, care being taken that there are no air bubbles present or the effect will not be clear. Warm the glass a little before pouring the filler as acrylic gives off heat as it hardens and might crack cold glass.
Acrylics can be bought ready coloured, or can be tinted with powder pigments and made opaque so that it looks like china, rather than glass, so it is quite useful for repairing china of a self colour which requires no further overpainting. Jasperware may be repaired satisfactorily with acrylic.
Surplus acrylic is cleaned from the edges of the join immediately, while it is still liquid. It can be abraded and rubbed away after hardening but this dulls it and there is the danger of scratching the surrounding glass. Acrylic can be polished with silicone carbide spaced grit cloth or paper, grades 150, 24o and 320.
Sometimes you may need a large lump of pseudo glass for a restoration. Acrylic can be poured into a mould, but this means that a model must first be made, and then a mould as described in the sectionon casting and pressing china parts. It is much easier, really, to make the lumps out of Perspex as this material is worked in exactly the same way as wood, and turned on a lathe. The tools—saws, files, drills etc. are lubricated while working with ordinary soap, and the Perspex will have to be polished when all shaping has been done.
Pieces of chandeliers can be replaced with Perspex, and new pedestals made for glass ornaments (see under Perspex).
Let the repaired piece cool down completely and then soak it in water to remove the gummed strips. There will be some spots of adhesive along the join squeezed out when the jour was made and deliberately not wiped away. Rub the spots very carefully with glass paper and break them down before removing them with a scalpel or a razor blade. This cleaning is quite a delicate operation and if done without abrasion may result in lifting little chips of china or
glaze.
If the crack was also c’., Red and Aralditc with colouring was used, tidy the filled chips with fine glass paper, and over-paint or glaze if necessary.
Moulding aped Modelling whole pieces of a pot or a
figure are missing, the gap can be filled by rebuilding the piece with epoxy resin composition filler. But it isn’t quite so simple as that! Perfectly satisfactory pieces for plates, vases, bowls, statuettes etc. can be moulded or modelled and simply stuck into place provided the piece is not going into domestic use, but such mends are not strong
g enough
to withstand hard wear for very long unless they are sup- ported by metal cores or pins. It is easy to mould or model a jug handle without a core, but unlikely that it will last very long if the jug is used. If the new handle has a core it will be very strong indeed. The making of cores and pins is described in a later section, and here I shall talk about moulding and modelling without supports. The techniques involved are almost identical when supports are incorporated. The job requires only a few cheap tools until the moment when you get involved in metal work and drilling for supports. And many people, once they reach this stage, just take the work to an expert restorer rather than buy drills and bits etc.
Before mending a piece such as a bowl or plate or vase, without using a core, scratch or file the broken edges so that the new piece of moulding will lock into the edge as it sets. The danger is that your new pieces may not adhere too well to the smooth and thin edge of a break without some kind of roughness in which to get a grip, as the problems of adhesion are not quite the same as those of sticking two edges, of porcelain or pottery together.
Next, a backing is necessary. This means a surface up against which you can press the filler to remake the piece. If the object is a flat plate, with : flat surface, the same gummed strip as is used for binding can just be stuck on the outside surface of the piece completely covering the broken area. As it dries it stretches tight and makes a good smooth surface up against which to press the filler. This gummed paper cannot be used on a curved surface because it pulls taut and flat across the curve as it dries. Therefore the mould will
wihave to be made with a flexible material which will take a curve. Plasticine does the job well, but it never sets hard and can be pushed out of shape rather easily. Wedge plasticine before use—this is a potter’s term meaning quite simply banging it until it has no air bubbles in it. A mallet or a wooden rolling pin make good bashers for plasticine.
If you use plasticine for the mould and Araldite for the filler you will have to get some cellulose acetate to use as a parting agent as the two react upon each other and must be separated by coating the surface of the plasticine which will come into contact with die filler.
There are other moulding materials. The dental impression compound Paribar is more expensive, but is quite excellent for the work, and is worth the extra money for it can be used again and again, needs no parting agent, and has other uses. Paribar is softened in hot water before use and resets fairly hard but is flexible enough to be extricated from quite deeply cut castings.
Making Moulds. Imagine that you have to replace a curved piece with a fluted surface, from the edge of a bowl. The whole of the edge of the bowl is fluted in the same way so you take an impression of a matching piece of the pattern oil a sound section of the edge. ‘Wet the surface of the bowl and press a slab of plasticine (about half an inch thick) on to a section just a little larger than the missing piece. Carry the plasticine up over the rim of the bowl so that it will be marked but don’t bend it too far round the rim if there is any ridge or it may be difficult to remove the plasticine without bending it. Press the plasticine well and truly until you are satisfied that you have made a perfect impression. Lift it carefully off and place it over the hole on the outside of the bowl in exactly the right place so that the pattern is continuous. Press it lightly so that the broken edges of the china mark the plasticine, then remove the plasticise, and paint the area inside the edge marks with cellulose acetate parting agent, then replace it over the hole. It will stick to the dry china round the edges of the break. Bend over the top sections of plasticine away from the hole, round the rim of the bowl to keep die mould in place. A few strips of Sellotape across it and on to the china will help. Don’t use gummed strip, for this will dry out and flatten the mould. The Scllotapc may give slightly but will help to avoid the disaster of the mould coming off the pot in the middle of die filling operation which follows.
Paribar can be used in exactly the same way to make a mould especially where there is a deeply indented pattern in the china. The Paribar goes hard, but it can be softened with swabs of boiling water and removed from die filler section without breaking it when the job is done. No parting agent is needed so that the Paribar can be put directly on to the break and left there.
Filler Composition and Filling. Now to mix up sonic filler (see Fillers and Cements). Araldite two-tube epoxy resin is first mixed together and then titanium dioxide (or other whitener) is added until the mixture has a nice doughy consistency. This mixture is a bit sticky and clings to tools and fingers. Keep a little dish of the powder handy, and another dish of Methylated spirits. Dip your fingers in the powder, and the tools in the Meths from time to time, and you won’t get so stuck up. When dried out this filler looks exactly like biscuit, or unglazed baked china and takes overpainting very well. It also sticks directly to the edges of the break and you should have no trouble in making a perfect join. It isn’t the easiest of jobs to make and handle this filler, but the result is so good that it is worth practicing to get the mixture of the right colour and consistency.
Kaolin mixed with Araldite in the same way makes a very stiff, not quite so sticky, more translucent and buff coloured filler, but it has the disadvantage of not sticking quite so well to the edges of broken china as does the first mixture.
Isopon polyester resin filler is a paste which is mixed with a hardener. It is excellent for filling big holes as it dries quickly, but this means also that you must be able to work quickly. When using Isopon make all inside mould of the break as well, and having filled the mould, put the second inside mould oil to the filler from the inside to get a smooth interior surface, pressing it down well. Isopon requires no parting agents. Although it will stick to itself so that it call be built up in layers, it will not stick to china, so when the moulds arc removed, the new Isopon piece will come away and will have to be stuck in just like an ordinary broken piece. It can be rubbed and filed to finish it off It cannot be used as an adhesive.
Bondapaste is another excellent filler which hardens quickly and does not have to be baked, nor does it require powder additions to make it opaque. It does not dry white, but this is immaterial if you are going to overpaint it any-way. It can be used as an adhesive or cement and when used as a filler it stays in place without further adhesives. It can be filed, carved and abraded within a quarter of an hour of use, so is a very time-saving material, once one is experienced enough to shape it quickly.
The exact consistency of any filler is difficult to describe and can only be discovered by trial and error. If it is too hard it will push the plasticise out of place as you press it into the mould. If it is too runny it will tend to run into the lower part of the mould in whichever place you are holding it, and will not make a piece of even thickness. If the mould is made of Paribar then a stiffer nix of filler can be used.
The mixture is worked into the aperture with a round ended tool. Boxwood potter’s modelling tools are excellent but many things make good modelling tools. Some workers like to prop the pot up as they work, others hold the pot in one hand so that the break with its mould is cupped and held in position while the filler is worked in. Great care must be taken to make sure that the filler goes into all the corners and crevices right up to the edges, with no air bubbles trapped underneath. Smooth the inside surface with the tool and with thumbs and fingers until it is as like the surrounding inside surface as your eye can judge. Setthe pot aside for an hour, if the filler is Araldite, by which time it will have set to a rubbery consistency and can be worked further if necessary. If a quicker setting filler has been used, once it has set hard it can be carved, filed and abraded until it is absolutely perfect, and it is then ready for overpainting.
To speed up the setting of a mend done with Araldite, bake the pot for half an hour at zoo deg. F. If there are any small cracks or pits in the surface fill them with a thin mixture of filler, using a water-colour brush.
Chips. The mending of chips, big and small, which do not go right through a piece, involves work which is halfway between the filling of apertures as described above, and modelling
which is described in the next section.
Quite simply, you make up a mixture of any of the above mentioned fillers into a fairly stiff mixture and press it into the previously cleaned and dried area of the chip and smooth it until it looks right. Don’t get air bubbles under the filling. Wheel chips—large chips on the edge of a piece—should first have a thin layer of adhesive, to help bind the filler in place. The art of filling chips is to get a good blend along the edges and to get the filling neither too proud nor too shallow, and in getting the composition in so that no air bubbles remain behind to raise it in due course. If you suspect that a little air is trapped, prick the filler with a pin and press it down again and fill tip the pin hole.
Allow the filler to dry out over a hot radiator and then, when it is hard, rub it down with glass paper until you are satisfied that the chip, after overpainting, will be indistinguishable. Pick up the piece and squint at it at eye level in all possible planes, and rely on the sensitive tips of your fingers run across the mend to detect any irregularities. If even at this late stage the chip is not properly filled, more composition can be added for it will stick to itself, and the process repeated until you are satisfied.
Modelling. When neither straightforward sticking, nor press moulding can be used to mend an object, try modelling. It is impossible to make a mould for a missing piece which is not a repetition of another part of the object, as described previously. The missing piece just has to be built up from scratch and the result depends on the artistic ability of the restorer. Large modelled sections will have to have metal supports—dowels, or pins, or strips—and the techniques will be described later on. I am still concerned with the techniques which do not include drilling.
When a part of a plate, or a vase, or perhaps a lid knob must be remodelled, take a piece of rather doughy filler composition and roll it either flat for a flat section, or into a ball for a knob, or into a sausage for a handle, in an approximate size and shape for the job. Then press it firmly to the edge of the broken part, and model it with Boxwood tools, fingers and any suitable home made tools that you may fancy. Whenever epoxy resin mixtures are being used, dip the tools in methylated spirit to avoid sticking.
Modelling becomes really interesting when a porcelain object such as a figure or perhaps a vase festooned with flowers and leaves has pieces chipped out or broken off and lost. To remake flowers and leaves is not at all difficult. Any woman who has ever made an apple pie with a decorated crust knows the technique. The pastry, in this case filler composition in a nice doughy mixture, is rolled out to the thickness of the petal or leaf required and then pieces are cut out of it in the flat. A small sharp knife or scalpel can be used as a cutter, shapes having been first marked out with a darning needle or a fine graver. Or, if the leaf or petal pattern is to be repetitive, a cutter can be made out of strip brass or copper foil, beret to make the appropriate shapes. Make a template or pattern out of plywood, using a fretsaw (see Fig. 8). Tack this pattern to your work bench with a central nail and then hammer a copper foil strip round it with a small hammer until it is exactly the same shape. If the template is pinned with a central nail it can be pivoted round as the cutter is being made so that all pieces can be reached.
The cutting of different species of flowers, daisies, roses, apple blossom etc. is hard to describe exactly. It is a matter of careful observation of thepetals which are to be matched, and of measurements with calipers and dividers, if your eye is not good enough. Petals are cut out in flat shapes and bent over slightly at the edges, and rolled into concave shapes etc. Once your petals and leaves arc made they are then fixed to each other and to the main piece, and there is no great difficulty about this unless the anchorage point is very small indeed, especially if you arc using a good adhesive filler composition such as Araldite and titanium dioxide. it is often possible to add an extra leaf, or to put in
small
a smasupport of composition disguised in some way as part of the decoration, which will hold the modelled part in place. Most people have a collection of tools for modelling which they have made specially to get into different corners ; sewing needles, bent knitting needles, scalpels, spatulas, rifflers, spikes and blades of all kinds, even old hacksaw blades, conic in usefid.
When pieces of an object are missing for which no pressed mould can be made, it is still possible to make a mould out of plasticise which approximates pretty closely the missing piece, and to put this on to the whole in such a way that the aperture can be filled with composition in exactly the same way as a pressed mould is filled. Then the new piece must be rubbed and shaped to final perfection after the setting or baking process has been completed; but
this can be a slow job.
There are problems when it comes to modelling difficult things like faces; it rather depends upon how clever you are, but there is yet one more way, which involves modelling. It is a much more complex and tricky job, but it can save such a lot of time and trouble in the long run, -aid once again may enable you to get away with it without resorting to pinning and dowelling.
Make a model, in plasticine, of the missing part. Actually this is easy if you have a talent for modelling, terribly difficult if you haven’t. Say for instance that half a leg and a foot are missing from a figurine. Using calipers and dividers, measure the other leg and foot exactly, so that at any rate lie won’t have a size six left boot and a size ten right boot. Then model a plasticine leg to the right diniensions and in the kind of position in which it looks as if it ought to be, and keep trying your model in the space until it satisfies you. Plasticine doesn’t harden so take as long as you like over making the model.
Having made your plasticine model, a mould must be made from it and a cast or pressing taken from the mould. The finished cast can simply be stuck into position (or dowelled or pinned if necessary).
Take a sheet of glass, and a large lump of plasticise. Roll the plasticise out into a very thick strip and lay it on edge on the glass (see Fig. 9) in a square or a circle plenty big enough to hold the model, horizontally. Then fix the model, horizontally, halfway up one side of the container that you have just made. A peg carefully inserted into the end of the model and pushed out through the container side should hold it into position. Then prepare some plaster of Paris. Into another container which can be handled easily and has a pouring lip, put enough water to half fill the mould container, and sift plaster of Paris powder into it until the mixture is the consistency of thick cream, stirring with the hand to break up lumps. Then pour the plaster of Paris mixture into the mould until it is halfway up the model. Leave the whole thing to set. Then cut two wide grooves or shallow holes out of the plaster.
sure that it is really well drenched and that no tiny part has escaped swabbing. This acts as a parting agent between the two halves of the plaster mould. Make another mix of plaster as before and pour this nito the mould until the model is well covered. When this has set, remove the plasticine case and case the two sections of the casting apart. Take out the original plasticine model and you should have a perfect mould in two halves. This mould will have two locking pieces where you cut the grooves or shallow holes so that when the two halves are put together again they will locate exactly, and at the end where the model was attached to the side wall of the plasticine container, there will be a hole.
Now you have a mould which can be used to make a casting or pressing of your original model. Smear a film of silicone grease all over the pattern sections of the mould to prevent the filler sticking to the plaster of Paris, and then make up enough filler composition to fill the two halves of the mould. This filler should be soft enough to flow freely into the mould sections. When the two sections are filled, bring them together and bind them tightly with wire. Ram the composition well home, through the hole. Leave the mould, with the hole at the top, for two hours to set, and then, if you are using epoxy resin, bake it for half an hour at 2oo deg F.
Undo the wire binding and take off the plaster. If you have not used a parting agent, the plaster can be cut out and broken away and the last of it scrubbed off the model. Stick or dowel the finished model to the whole, having
made sure that the edges fit perfectly by filing and abrading. bradin,
Any discrepancy in fit which is too big to be put right by filing, can be filled with some filler composition.
Moulds can also be made from pieces of porcelain similar to the piece you are trying to replace, and then pressings made from these can be carved, filed, abraded, and built up to fit exactly.
Instead of plaster of Paris, rubberised solution such as Qualitex can be poured around your model. The advantage of using this material is that the mould is flexible and will come off difficult undercut models without damaging them. Rubberised solutions, therefore, are best for making moulds from models which must not be damaged in any way. The technique is much the same as that described above. A plasticine container is built up round half the part to be copied, and the solution is poured in.
The process is repeated on the other half and you then have the complete mould in two sections. Details vary with each job.
Faces on statuettes are very alike, and differ only iun detail of hair and headdress. There is no reason why, if you collect figures, you should not make a series of moulds or masks from any statuettes that come your way, and so build up a stock of faces iii reserve for the day when they may be needed.
Incidentally, the principles of making casts, moulds, pressings etc. are generally similar for work in all kinds of materials, and many restorers of objects other than china, such as old guns and pistols, make their own metal castings. It is a skill which has so many applications, not only for restoration but for creation. Modem materials make exciting castings and pressings, and it is an art well worth studying for its own sake.
