Beat the dust out of them as clean as possible, then rub them over
with a dry brush, and make a good lather with Castille soap, and rub
them well over with a hard brush, then take clean water and with it
wash off the froth; make a water with alum, and wash them over with
it, and when dry, most of the colours will be restored in a short
time; and those that are yet too faint, must be touched up with a
pencil dipped in suitable colours; it may be run all over in the same
manner with water colours mixed well with gum water, and it will look
at a distance like new.