For this color naturally gray feathers may be used if a deep shade is
to be dyed; for light shades they ought to be bleached. Scour and rinse
the feathers well; then prepare a bath with five per cent., of the
weight of feathers, bisulphate of soda, to which add azo orange, acid
violet and extract of archil. Dissolve the dyestuffs, each separately
in water, filter, add the clear solutions gradually in small quantities
until the shade is nearly reached, then, in order to correct, by
drops, until the exact depth and tone are obtained. Enter the feathers
and dye to shade at 170° F. Instead of acid violet indigo carmine
may be used; in this case, however, as the dyestuff runs up slowly
and difficultly, work at 170° F., for twenty to thirty minutes, then
raise the temperature slowly to near the boiling point and continue at
that temperature, without actual boiling, until the required color is
obtained. Then rinse, squeeze, starch and dry.
Bronze is also produced like drab, that is, with azo orange, acid
violet and fuchsine S., but with greater quantities of dyestuff.
Bronze is also obtained with the recipe for any dark brown, by making
the yellow in it predominant; particularly good bronzes are in this
manner obtained from dark chestnut brown.