_To fix the colours by melting the wax._
When your picture is finished and dry, have a good clear fire of
sea-coals,[8] approach your picture with the painted side towards it,
at about two feet distance, let it grow warm by gentle degrees, always
approaching nearer, till within a foot distance from the grate, but
never closer, holding your picture perpendicularly or a little inclined
as you shall find necessary. If the picture is large do one half first,
then the other; there is not the least difficulty for any size.
When you perceive by the hue and shining of the painted surface that
all is perfectly absorbed; then remove it gradually from the fire as
you advanced it, and your picture will be done.
If you see any place defective for want of a sufficient quantity of
wax,[9] put a little finely scraped wax on the back of that place, then
bring only a red hot poker, or some such thing towards it, the wax will
immediately settle in its place. If there are many parts so defective,
put scrapings of wax there, and bring the whole picture before the fire
as above mentioned. There is no danger in bringing the picture to
the fire as often as required, provided you never give it too great
a degree of heat; if you do, the wax will raise in bubbles upon the
surface, and your picture will look rough and uneven.
Advance your picture never too hasty, nor retire it too quickly; if
you do the former, the sudden action of the fire might disturb some of
the colours; if the latter, the wax will not retire enough within the
texture of the cloth, consequently lye too much above the colours and
look glaring. If you perceive any such glaring spots or places upon
your picture, or (in other words) parts that appear varnished like,
and that appearance should proceed from too great a quantity of wax,
paint those places over on the back with whitening, or any one of your
other colours, and when dry bring the picture near the fire, as above
mentioned, and those colours or whitening will imbibe the overplus of
the wax. Repeat that if required.