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 (Koenigswæter & 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.