BLEACHING OR DECOLORING NATURALLY GRAY FEATHERS.
The feather dyer is often required to dye light colors upon naturally gray or even black feathers. As above remarked, the natural color would show even under dark colors dyed upon them to a greater or less extent, unless they are first decolorized, that is, their natural color destroyed or blackened. Much more necessary is, therefore, this operation for light colors to be dyed upon naturally colored ostrich feathers. The only known chemical agent affecting such a bleach to nearly white is peroxyd of hydrogen or oxygenated water. For bleaching ostrich feathers a bath is prepared of peroxyd of hydrogen to which so much liquid ammonia is added as to give the bath a sharp pungent odor. The feathers, which must be previously cleaned as above mentioned, and well rinsed, are entered and left immersed in the bath until they have assumed a nearly white cream color, whereupon the feathers are taken up and thoroughly rinsed or laid down in running water until every trace of ammonia has disappeared. It must be observed, however, that only acid aniline colors can be dyed upon such decolorized feathers and that in dyeing only a moderate heat must be applied.
Dr. P. Ebell, of Linden, near Hanover, one of the first and still largest manufacturers of peroxyd of hydrogen, writes on the subject of feather bleaching as follows: The assorted and picked feathers are cleaned from dirt and fat with soap and water by means of soft brushes, which operation is continued until the feathers (after drying) are readily wetted by water; when they are laid down for some time in pure water. The liquids are removed from the feathers by a centrifugal machine or a wringer (the latter is evidently meant for ordinary feathers, other than ostrich feathers). Mix in a clean wooden tub twenty litres peroxyd of hydrogen (Kœnigswæter & Ebell) with four hundred and fifty grammes ammonia 20° B. (=0.9 sp. gra.) and heat to 34° C., by a leaden steam pipe at the bottom of the tub. Enter 5 kilo. cleaned feathers, which work by hand and turn every hour. In twenty four hours the bleach is completed. If pure white feathers are wanted, give a second bath, but for a shorter period. The bleached feathers are carefully removed from the bleaching bath and laid down, for an hour and a half, in a cold bath of one hundred litres water containing one hundred grammes sulphuric acid 66° B., and then completely lixiviated in pure, soft water. While moist (after squeezing) they are then passed through a milk of unboiled starch which is lightly blued with aniline blue or violet, and slowly dried, in the air or in a warm room, under repeated shaking to prevent the flues from sticking together. After removing the starch by beating, the feathers are ready for curling, etc.