The Artist's Assistant, In the Study and Practice of Mechanical Sciences: Calculated for the Improvement of Genius. Illustrated with Copper-Plates (Birmingham, [ca. 1785])

THE ARTIST'S ASSISTANT. 189

or any lefs proportion of the brafil. according to the
colour cleared.

Of ftaining horn to imitate tortoife-fhell.—The
horn to be ftained muft be firft preffed into proper
plates, or fcales, or other flat form. The following
mixture muft then be prepared :

£: Take of quick lime two parts, and of litharge
c: one, and temper them to the confidence of a foft
" pafte with foap lye."

Put this pafte over all the parts of the horn, except
fuch as are proper to be left transparent, in order to
the greater refemblance of the tortoife-fhell. The
horn muft then remain thus covered with the pafte
till it be thoroughly dry ; when the pafte being
brufhed off, the horn will be found partly opake, and
partly tranfparent, in the manner of tortoife-fhell;
and when put over a foil, of the kind of latten call-
ed affidue, will be fcarcely diftinguifhable from it.
It requires fome degree of fancy and judgment, to
difpofe of the pafte in fuch a manner, as to form a
variety of tranfparent parts of different magnitude
and figure, to look like the effect, of nature ; and it
"will be an improvement to add femi-tranfparent
parts. This may be done by mixing whiting with
fome of the pafte to weaken its operation in particu-
lar places, by which fpots of a reddifh brown will
be produced ; that if properly interfperfed, efpecially
on the edges 01 the dark parts, will greatly increafe
as well the beauty of the work, as its fimilitude with
the real tortoife-fhell.

To ftain ivory, bone, and horn, black__-Proceed

in the fame manner as is above directed for wood.

Of ftaining paper, or parchment, yellow.—Paper
may be ftained yellow by the tincture of French

berries.