Prepare a slightly acidulated warm bath with three per cent., of the
weight of feathers, fast aniline brown, one per cent. azo yellow, one
percent. extract of indigo, and a little sulphuric acid; enter the
well scoured and rinsed feathers at 120-140° F., work the feathers for
one-half hour, while slowly raising the temperature to the boiling
point; continue dyeing at that degree of heat, but not boiling, for
five minutes; lift, rinse, starch and dry.