HOW GOLD AND SILVER ARE LAID IN BOOKS.
Afterwards take pure minium (red lead), and add to it a third part of
cinnabar (vermilion), grinding it upon a stone with water. Which being
carefully ground, beat up the clear of the white of an egg, in summer
with water, in winter without water; and when it is clear, put the minium
into a horn and pour the clear upon it, and stir it a little with a piece
of wood put into it, and with a pencil fill up all places with it upon
which you wish to lay gold. Then place a little pot with glue over the
fire, and when it is liquefied, pour it into the shell of gold and wash
it with it. When you have poured which into another shell, in which the
purifying is kept, again pour in warm glue, and holding it in the palm of
your left hand, stir it carefully with the pencil, and lay it on where
you wish, thick or thin, so, however, that there be little glue, because,
should it exceed, it blackens the gold and does not receive a polish; but
after it has dried, polish it with a tooth or bloodstone carefully filed
and polished, upon a smooth and shining horn tablet. But should it
happen, through negligence of the glue not being well cooked, that the
gold pulverizes in rubbing, or rises on account of too great thickness,
have near you some old clear of egg, beat up without water, and directly
with a pencil paint slightly and quickly over the gold; when it is dry
again rub it with the tooth or stone. Lay in this manner silver, brass,
and copper in their place and polish them.
The raised gold was not always produced by the mixture of red lead and
white of egg recommended by Theophilus. It was, especially in Italy,
frequently made of a composition of "gesso," or plaster, and in the 15th
century was often punctured all over by way of ornament. It may be
occasionally met with stamped over in patterns, with intaglio punches. This
"gesso raising," though very brilliant, possessed little tenacity, and in
many examples it has scaled off, while the more ancient "raising"
prescribed by Theophilus has adhered perfectly.