While many in the trade do not make a distinction between drop black or bone black and ivory black, the latter, nevertheless, is, or at least should be, made from the waste of ivory in turning and cutting of ornaments, etc., but, as there would not be enough to go around for the demand of the trade, the manufacturers of ivory black make use of animal bones, selected especially for this purpose, especially the knuckles and shins of bo-vines, while ordinary bone black of extra fine texture and hue is also sold under the name of ivory black. The chief features that distinguish ivory black from ordinary bone black are greater fineness and brilliancy, and that it contains a higher percentage of carbon, which runs between 17 and 18 per cent, as against 14 to 15 per cent in ordinary bone black. While the specific gravity of bone black is 2.70 on the average, ivory black has a gravity of 2.60 to 2.65, but resembles bone black in all other respects, excepting fineness and depth. The best ivory blacks were obtained from the Taunus in Germany, through some German and English exporters, and the selling prices at one time were rather high, in some of the better grades reaching four or five times the price of ordinary powdered bone black, and even now it is treble that of the latter. As to the grinding of ivory black, all that has been said in reference to bone black applies here, excepting that a trifle more vehicle is required for mixing and grinding in oil as well as in japan.
Unless specifically required, ivory black is not ground in oil for the trade, but bone or animal black is so labeled. For the use of the coach and carriage trade, however, ivory black is ground in coach japan or gold-size japan and sold at an advance in price under the label of "Coach Ivory Black" or "Ivory Drop Black." As it was the custom of the manufacturers of ivory black to add some blue, either Chinese or Prussian blue, also ultramarine blue, to the black to increase its depth in oil, the color grinder must look sharp toward avoiding the use of a blued ivory black when grinding it in japan or varnish for this trade, for the reason that the user thins the black with turpentine, which will make the blue float to the surface, and in finishing the surface with varnish there will be a smoky or greenish effect, according to the nature of the blue used. There is no black pigment that excels ivory black in brilliancy for fine coach and carriage work, and for high-grade enamel making a base made by grinding ivory black in varnish has no superior. The proportions of black and varnish required vary according to the consistency of the varnish used in grinding. Ivory black is supplied to artists ground in poppy seed or nut oil, although there seems to be no special reason for selecting such a vehicle, as linseed oil, well settled by age, will serve the purpose fully as well.