Alexander Paul, The Practical Ostrich Feather Dyer
“ Prepare a handwarm bath with a little tartaric acid or acetic acid, to which some solution of eosine, rhodamine, azoeosine, safranine, coccine or ponceau 6 R. B. or ponceau R. R. Be particularly cautious in adding the dyestuff solutions gradually in small quantities, even by drops, to avoid over-dyeing, as by partly stripping of a too dark shade, a fine color can never be obtained, and the nature of the material demands that all unnecessary handling be avoided. After dyeing, rinse lightly, pass through starch and dry. The dyes with the ponceaus are faster than those with eosine or safranine. ”
