Scour and rinse the feathers well. Prepare a boiling hot bath slightly
acidulated with sulphuric acid, to which add a liberal quantity of
ponceau 6 R. B., a few drops solution of aniline blue, and some yellow
dyestuff, such as turmeric, fast yellow, or quinoline yellow, and bring
the bath to boil for a few minutes. Then chill to sharp hand-heat,
enter the feathers and work until level, and sample; if still too
light, add some more of all these dyestuffs. As the bath shows from
the beginning the color it will produce, it can be corrected before
entering the feathers.