Jul 31

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).

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