I. Scour and rinse well; prepare a warm bath, in which dissolve three
per cent., of the weight of feathers, alum, add twenty-five per
cent. extract of archil, one and one half per cent. azo yellow, and
if required for shade, one-half per cent. indigo carmine; enter at
170° F., dye to shade while slowly raising the temperature to near
the boiling point, continue at that temperature for ten to fifteen
minutes longer; then lift, rinse and dry. Instead of indigo carmine,
cloth-blue S. may be used, in which case enter at 120° and raise the
temperature slowly, not above 190° F. Or,
II. Prepare a bath at 190° F., add five per cent. bisulphate of soda,
when dissolved, add solution of extract of archil, fast yellow and
indigo carmine as required for the shade, and dye at that temperature
to sample. Instead of archil, any red or orange azo dyestuff may be
used, preferably bordeaux.