Miscellaneous DIY 6 | uWoodcraft.com

The following is a quick guide to polishing and staining ivory. Polishing Ivory To give a fine finish to ivory it is essential that the tools be perfectly sharpened. The plain portions of turned pieces which are intended to be left plain, or subsequently ornamented, are first prepared for polishing with pumice powder and water applied with a piece of flannel, into the surface of which the particles of powder will "bed" themselves. The action of the pumice powder is that of smoothing, and the smoother the prepared surface, the better the polish that can be given. The process therefore should not be hurried. The amount of water mixed with the pumice powder is important, as should it be insufficient, the best possible smoothness will not be obtained. The application of the "rubber" charged with the pumice powder and a plentiful supply of water, should be such that the flannel is not allowed to remain on any portion of the revolving work for more than a moment. The rubber should be continually moved from one position to another. After this operation with the pumice powder and water the remaining grains of powder should be removed with fresh water and a sponge, in order to avoid fine scratches or other irregular surfaces when the polishing is completed. The work is now polished with whitening and water, mixed to the thickness of skim milk, i.e. very thin and watery. The same technique is used as with the pumice powder, When this has been done thoroughly, the flannel should be more and more saturated with water, without taking up any more whitening, until finally the work is being bathed in flannel innocent of whitening. The work is now removed from the chuck, washed with soap and water, and finally rinsed by allowing water from the tap to run freely over it. It is then carefully dried, left for an hour or so, and it will then take a frictional polish which, if the above operations have been carefully carried out, will leave little or nothing to be desired. Polishing Ivory When Further Cutting is Intended All the foregoing remarks refer to ivory which has been plain-turned and which is not intended for tooling with revolving cutters. Where such further cutting is intended, the polishing as described above first takes place, the only difference being that the work is not removed from the chuck. When the pattern has been out with revolving tools the facets are polished with a small brush using whitening and water. This is done with a certain amount of caution. The brush should as far as possible be rubbed along rather than across the facets, as otherwise they tend to become blunted. It should be stressed that any attempt to polish indifferent cutting, due to imperfectly sharpened tools will not be successful. The prolonged cutting action of the whitening will also tend to intensify the bluntness of the high parts of all faceted work. There is an alternative to polishing plain turned work as outlined above, and that is the use of Bluebell metal polish. It avoids the risk of splashing water on the lathe bed and the polish obtained is equal in every respect to that obtained from whitening and water, and is achieved much more quickly as the ivory does not need to be dried. Ivory Which Will Not Take a High Polish It may be mentioned here that there is ivory which will not take a high polish. Fossil ivory, in which the natural gelatin has diminished with age, will not take such a brilliant polish as that from the head of an animal shot in recent years. Matching Ivory When turned objects are composed of more than one piece it is essential in the interests of economy to select from various pieces in hand those that will match for color. This is no easy matter, because of the surprising variety of-shade. A large stock of ivory is necessary if one is to get perfect uniformity of color. The alternative, of course, is to make all parts of the object from the same tusk, but this usually is wasteful and therefore entails avoidable expense. In matching it is difficult to make a satisfactory selection when one component of the ultimate assembly is turned and polished, because the mere fact of polishing seems to modify the color, and in matching two pieces of turning not made from the same tusk some difficulty will be found. The writer has found that the turning and polishing of each piece is the only real test. One can then see if any real discrepancy of color exists. Staining Ivory To stain ivory red, a definite sequence of operations is essential. First the work is polished and then the surface gelatin is removed to ensure uniformity of staining. This is done by placing the work in a bath of diluted nitric acid, i oz of acid to 1 quart of water. Leave the ivory in the acid solution for a few minutes, taking care that there are no air bubbles on the surface of the ivory. The diluted acid is then poured off and the work thoroughly rinsed beneath a running tap until all the solution has been washed away. The work is then ready for staining. The stain used is an aniline scarlet, supplemented with a very small quantity of cochineal. The correct proportions are are l oz of scarlet to 1 quart of water, plus a small quantity of cochineal. This is warmed and well stirred and should then be strained through very fine muslin or an old silk stocking, either fabric being scrupulously clean of course. It is an advantage to prepare the stain a day or two before use. When needed it is placed in an enameled or aluminum saucepan and warmed, but not made hot. The pieces of work one wishes to stain are then placed in the warmed stain and allowed to remain in it for some 20 minutes. The ivory is then removed and thoroughly washed in running water. It should not be wiped, but allowed to dry in some sort of sieve. (A chip pan is excellent.) On the following day the stained pieces will be sufficiently dry to permit a frictional polish to be given.