OF THE KINDS AND THE TEMPERING OF FOLIUM.
There are three kinds of folium, one red, another purple, a third blue,
which you will thus temper. Take ashes, and sift them through a cloth,
and, sprinkling them with cold water, make rolls of them in form of
loaves, and placing them in the fire, leave them until they quite glow.
After they have first burnt for a very long time, and have afterwards
cooled, place a portion of them in a vessel of clay, pouring urine upon
them and stirring with wood. When it has deposed in a clear manner, pour
it upon the red folium, and, grinding it slightly upon a stone, add to it
a fourth part of quick lime, and when it shall be ground and sufficiently
moistened, strain it through a cloth, and paint with a pencil where you
wish, thinly; afterwards more thickly. And if you wish to imitate a robe
in a page of a book, with purple folium; with the same tempering, without
the mixture of lime, paint first with a pen, in the same page, flourishes
or circles, and in them birds or beasts, or leaves; and when it is dry,
paint red folium over all, thinly, then more thickly, and a third time if
necessary; and afterwards paint over it some old clear of egg. Paint over
also with glaire of egg, draperies, and all things which you have painted
with folium and carmine. You can likewise preserve the burned ashes which
remain for a long time, dry.
I conclude the series of receipts extracted from Theophilus[108] by one not
further bearing upon the Art of Illumination, than as proving the nature of
the ink which has generally retained its colour so wonderfully in the
ancient manuscripts.