When you want to gild you take the purest, cleanest, 24 carat gold,
& you beat it out with clean hammers on an anvil, until you get it
to the thinness of a sheet of writing paper. Then you cut up as much
as you want into small pieces. After this you take a new crucible
never yet used & such as goldsmiths melt silver and gold in, and
into it you put so much quicksilver, free from all impurities, as
may be needed for the gold you want to employ. The proportion is at
the rate of one ounce to a scudi’s weight, that is to say, one part
of gold to eight parts of quicksilver, rather less than more of the
latter. Note that you should first mix together the quicksilver and
the gold in a clean vessel of earth or wood, and you put the crucible
on a fire of glowing embers, but not using the bellows. When the
crucible is red you throw into it some of the mixed quicksilver and
gold, hold it over the fire, and with a glowing ember gripped in a
pair of tongs stir it thoroughly together. Your eye & the feel of
your hand will tell you whether the gold be dissolved and united with
the quicksilver. Great care has to be taken to aid the solution by
rapid stirring, for if you hold it too long, the gold, or rather the
amalgam will get too thick; if, on the other hand, you hold it on too
short a time, it will be too thin, and the gold not well mixed. The
great care which this requires can only be got by practice. When it
is all mixed & dissolved, & everything done in the manner described,
you take the hot mixture & pour it into a little beaker or vase in
accord with the amount of the gold you have mixed, and this vase is
filled with water, so that you hear it hissing when you pour the
mixture in. Then you wash it thus two or three times in other clean
water, till finally your water is quite clean and pure, and then you
set about the actual gilding as follows.
Wherever you want to gild on your work you have to get it well
polished & scratch-brushed,[174] for so it is called in the craft.
These scratch-brushes are made of brass wire about as thick as
thread[175] & done up into bundles about as thick as a man’s finger,
more or less, in accordance with the size of the work you want to
scrub, & tied round with brass or copper wire. Of course you can buy
these brushes at a grocer’s, but there they are usually sold only of
one size; so that your skilled workman if he wants to do his work
well, and has a large piece to do, binds up his own brushes himself
according to the size he wants.
After the scrubbing, you put the amalgam on with an
_avvivatoio_,[176] for so we call the little rod of copper set in a
wooden handle, & much the same size and length as a table fork; here,
again, the size accords with the requirements of your work. Carefully
then do you proceed to spread the amalgam over the places you want to
gild. True it is that some have put quicksilver on first, and then
spread the amalgam after, but this is not a good method, for too much
mercury dulls the colour and the beauty of the gold. Others, again,
have thought to do better by putting the gold on in successive times.
This I have likewise seen done, but have come to the conclusion that
the best way is to put all the gold on at once that you want for your
gilding, and then heat it over a slow fire, till all the quicksilver
goes off in fumes. If you notice that the gold on your work is not
even, you can, while it is still warm, very easily add on as much
as may make it so, till all is covered with gold. Then let it cool
by itself. I forgot to say in its proper place that if the gold
won’t stick on you will do well to have a little of the whitening
water[177] of which I told you above, and you dip your _avvivatoio_
with the gold in this water, & if that still won’t help you, take a
little aquafortis evaporated and weakened, and there’s no doubt that
will do it.
FOOTNOTES:
[174] _Grattapugiata._
[175] _Refe di cucire._
[176] _See ‘Vita,’ p. 252._
[177] _Bianchimento._