china riveting - China riveting china riveting - See also cements for china, cutting glazed tiles.
The riveting of china and earthenware, if carefully done, is the most substantial way of effecting repairs. The appearance is not usually as good as cementing, but in riveting china, one of the first rules is to put the rivets in the least conspicuous spots consistent with doing the job strongly. The "rivets," as they are called, are pieces of brass wire bent down at the ends, as in Fig. 1. The wire is about 1/16 in. thick and is flattened. The flattening may be done on one side only (the side that comes next to the china), in which case it is done with a file; or the two bent-down ends may be left of round wire, while the connecting piece is flattened a little by hammering. The idea is to get the wire to lie close against the china. If the rivet is to come on a curved surface, it is bent to correspond.
The holes are made in the china a little larger than the wire of the rivet, at about ¼ in. from the edge of the break, and slanting slightly downwards towards it, as Fig. 2, to correspond with the slight slant given to the ends of the rivet. The measurement of the holes and the rivets should be exact, and the latter should be made so that the ends will only just go in the holes, or will barely do so. In the latter case heat is relied on to expand and lengthen the rivet slightly, so that it will go in and then pull itself up tightly as it cools.
Without heat the rivet is made so that it has to be gently driven in with a small hammer or wooden mallet. The final fixing of the rivet is done, if hot with shellac, or if cold with plaster of Paris. The latter can be coloured if desired, and a little fluid plaster is well worked into the crack (after the riveting), to make it water-tight if it appears necessary. The holes drilled in the china should be of a depth of about half the thickness of the china, or a trifle more if the china is thin, and the turned down ends of the rivets must on no account be longer than the depth of the holes.
The drilling can be done by an archimedean drilling tool, or a hand brace, or a fiddle or bow drill, but the tool most commonly used, particularly by the peddling fraternity is an ingenious drill stock that can be made of three pieces of wood and a length of string, Fig. 3. The centre shaft is a rod about ½ in. thick, and say, 18 in. long.
The cross-piece to which the string is attached, is about 7 in. in length, the middle hole in it being a little larger than the rod. The circular piece acts as a fly-wheel, and may be 4½ in. in diameter, by 5/8 in. thick, and fits the rod tightly. By, holding the cross-piece, then giving the rod a twist to start it, the string will wind itself on, as in Fig. 4; then, by pressing down the cross-piece the rod will be made to revolve, and if the pressure is relieved just as the string has become unwound, the impetus given the flywheel will carry the rotation on sufficiently to wind the string on again the other way. The cross-piece is then pressed down again and the operation repeated. The rotation of the rod is thus several turns one way, followed by a corresponding number of turns the other way, and so on as long as the cross-piece is worked by the hand.
The drilling point may be of steel, or of copper, as mentioned in the following matter, turpentine being used as a lubricant, but to start the hole through the glazed surface - which is the hardest part - a diamond-pointed drill as Fig. 5 is sometimes used.
This is a piece of diamond (the kind used in many larger drilling tools) firmly secured in the end of a tin tube, either by cementing or soldering. This tube slips on to the lower end of the rod of the drilling stock just described.
Ceramic objects can be readily drilled with hardened steel tools. With majolica and porcelain without glaze it is best to drill under water; for instance, filling the vessel with water and placing it in another vessel filled with water, so that the drill is used under water and passes again into it after penetrating the material. Instead of filling glazed articles with water, a piece of cork may be placed under the spot where the drill is working. The pressure applied to the drill varies according to the hardness of the material; it must, however, gradually decrease as the drill approaches the point of exit, and finally cease altogether in order to avoid splintering. For enlarging small holes already existing it is best to use three-cornered or four-square broaches, ground smooth, in the same manner as above described (under water); for hard material, such as glass and glaze, moisten the broach with oil of turpentine. The simultaneous use of oil of turpentine and water is best in all cases, and especially when the object to be drilled does not permit the sole use of the oil as in the case of majolica and unglazed porcelain, as the oil will be absorbed if water is not used.
Boring the holes is generally done with a diamond-pointed drill or copper bit with corundum or emery. To make cutting tool, take piece of stout copper wire or rod, and fit to drill. See that it is perfectly straight. Next make the copper red hot, and plunge into cold water. Now take bit of hard wood, say box or oak, about ¼ in. to ½ in. thick and 1 in. or so square. Drill hole in it just large enough to take copper bit, put a few grains of emery powder in the hole, and insert copper bit. Press down firmly, and give a few turns. Add more emery, repeat process until end of copper is embedded with grains of emery. The bit requires renewing with emery at intervals, and can be kept moist with turpentine, or paraffin, or camphor dissolved in turpentine.
To Drill Glass
In drilling glass stick a piece of stiff clay or putty on the part where you wish to make the hole. Make a hole in the putty, exposing the glass to the size required. Into this hole pour a little molten lead, when, unless it is very thick glass, the piece will immediately drop out.
To File Glass Utensils.
Dip the file in strong caustic soda lye, and then, while still wet into coarse sand. With a file thus prepared glass utensils can be worked without cracking the glass.