Laying & paint that is a sort of gesso, called asiso, and it is made in
Burnishing this manner; namely, a little gesso sottile [see chap.

Gold n6> below], and a little biacca [whitelead], never more

of this than equals a third part of the gesso; then take a
little candy, less than the biacca; grind these ingredients
very finely with clear water, collect them together, and
let them dry without sun. When you wish to use some
to put on gold, cut ofiF a piece as large as you have need
of, and temper it with the white of an egg, well beaten,
as I have taught you. [The froth is allowed to stand for
one night to clear itselfl\ Temper this mixture with it; let
it dry; then take your gold, and either breathing on it or
not, as you please, you can put it on; and the gold being
laid on, take the tooth or burnishing-stone and burnish it,
but hold under the parchment a firm tablet of good wood,
very smooth. And you must know that you may write
letters with a pen and this asiso, or lay a ground of it, or
whatever you please—it is most excellent. But before
you lay the gold on it, see whether it is needful to scrape
or level it with the point of a knife, or clean it in any
way, for your brush sometimes puts more on in one place
than in another. Always beware of this.”

“Chap. 116.—How to prepare gesso sottile (slaked
plaster oj Paris) for grounding panels.

“You must now prepare a plaster for fine grounds,
called gesso sottile. This is made from the same plaster
[plaster of Paris] as the last, but it must be well purified
(purgata), and kept moist in a large tub for at least a
month; renew the water every day until it almost rots,
and is completely slaked, and all fiery heat goes out of it,
and it becomes as soft as silk. Throw away the water,
make it into cakes, and let it dry; and this gesso is sold by
the druggists to our painters. It is used for grounding, for
gilding, for working in relief, and other fine works.”

132

APPENDIX: ON GILDING

{By Graily Hewitt)

Success with raised gilding can only be expected when Laying &
practice has rendered attention to the details of the process Burnishing

automatic and there is no need to pause and think. Even Gold

then the results must be somewhat uncertain and experi¬
mental. For our own preparations of size are usually
unsatisfactory, and the ingredients of the best we can buy
are unknown to us. And our vellum is certainly not of
the quality we find in the old books. Some one is badly
wanted to investigate the chemistry of the one and an ap¬
propriate preparation of the other. But we can take as
much care as our time allows, passing nothing as “good
enough” which we have not well examined, and bringing
to the business all the patience and deftness available.

Vellum is too stiff, or too dry, or too greasy. When
stiff, it is too thick for books; when dry, too apt to crack
or cockle; when too greasy, exasperating. And yet the
soft and rather greasy sort can be rendered more agreeable
than the rest with labour. It should be rubbed by the
flat of the hand with powdered pumice (or even fine sand¬
paper on the rough side) and French chalk, especially
on its split (or rougher) side, until it is serviceable. A
few trials will teach how long to give to this. Five
minutes for one side of a lamb’s skin would not be too
much. It can then be beaten with a silk handkerchief,
but not rubbed with this until the size has been laid.

It may be rubbed cleaner between the laying of the size
and the gilding. Especially must those parts of pages be
thoroughly rubbed clean which in the book, when made
up, will lie upon and be pressed against gold letters
on the page opposite; or the pumice left behind will
scratch them. On the other hand, if the vellum has not
been thoroughly pumiced on both pages, the greasiness in

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