Very excellent will be a stiff white paper, made of the usual
mixture and filtered milk of an herb called calves foot; and when
this paper is prepared and damped and folded and wrapped up it may
be mixed with the mixture and thus left to dry; but if you break it
before it is moistened it becomes somewhat like the thin paste
called _lasagne_ and you may then damp it and wrap it up and put it
in the mixture and leave it to dry; or again this paper may be
covered with stiff transparent white and _sardonio_ and then damped
so that it may not form angles and then covered up with strong
transparent size and as soon as it is firm cut it two fingers, and
leave it to dry; again you may make stiff cardboard of _sardonio_
and dry it and then place it between two sheets of papyrus and break
it inside with a wooden mallet with a handle and then open it with
care holding the lower sheet of paper flat and firm so that the
broken pieces be not separated; then have a sheet of paper covered
with hot glue and apply it on the top of all these pieces and let
them stick fast; then turn it upside down and apply transparent size
several times in the spaces between the pieces, each time pouring in
first some black and then some stiff white and each time leaving it
to dry; then smooth it and polish it.

On the preparation and use of colours (618-627).