1. _Black dye._--If the ivory be laid for several hours in a dilute
solution of neutral nitrate of pure silver, with access of light, it
will assume a black colour, having a slightly green cast. A still finer
and deeper black may be obtained by boiling the ivory for some time in a
strained decoction of logwood, and then steeping it in a solution of red
sulphate or red acetate of iron.
2. _Blue dye._--When ivory is kept immersed for a longer or shorter time
in a dilute solution of sulphate of indigo (partly saturated with
potash), it assumes a blue tint of greater or less intensity.
3. _Green dye._--This is given by dipping blued ivory for a little while
in solution of nitromuriate of tin, and then in a hot decoction of
fustic.
4. _Yellow dye_--is given by impregnating the ivory first with the above
tin mordant, and then digesting it with heat in a strained decoction of
fustic. The colour passes into orange, if some brazil wood has been
mixed with the fustic. A very fine unchangeable yellow may be
communicated to ivory by steeping it 18 or 24 hours in a strong solution
of the neutral chromate of potash, and then plunging it for some time in
a boiling hot solution of acetate of lead.
5. _Red dye_--may be given by imbuing the ivory first with the tin
mordant, then plunging it in a bath of brazil wood, cochineal, or a
mixture of the two. Lac-dye may be used with still more advantage, to
produce a scarlet tint. If the scarlet ivory be plunged for a little in
a solution of potash, it will become cherry red.
6. _Violet dye_--is given in the logwood bath, to ivory previously
mordanted for a short time with solution of tin. When the bath becomes
exhausted, it imparts a lilac hue. Violet ivory is changed to purple-red
by steeping it a little while in water containing a few drops of
nitro-muriatic acid.
With regard to dyeing ivory, it may in general be observed, that the
colours penetrate better before the surface is polished than afterwards.
Should any dark spots appear, they may be cleared up by rubbing them
with chalk; after which the ivory should be dyed once more to produce
perfect uniformity of shade. On taking it out of the boiling hot dye
bath, it ought to be immediately plunged into cold water, to prevent the
chance of fissures being caused by the heat.
If the borings and chips of the ivory-turner, called ivory dust, be
boiled in water, a kind of fine size is obtained.
The importation of elephants’ teeth for home consumption was, in 1834,
4,282 cwts.; in 1835, 3,698, and in 1836, 4,584 cwts.; duty, 1_l._ per
cwt.
IVORY BLACK (_Noir d’ivoire_, Fr.; _Kohle von Elfenbein_, Germ.); is
prepared from ivory dust, by calcination in the very same way as is
described under BONE BLACK.
The calcined matter being ground and levigated on a porphyry slab,
affords a beautiful velvety black, much used in copperplate printing.
Ivory black may be prepared upon the small scale, by a well regulated
ignition of the ivory dust in a covered crucible.