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.
PEROXYD OF HYDROGEN.
This most valuable bleaching agent is a contraction of hydrogen and oxygen, of the formula HO2, sp. grv. 1.45 (chemically given), or 94.12 per cent. oxygen with 5.88 per cent. hydrogen. It consists in a limpid, syrupous liquid, of characteristic color, and when heated to 15° C., is decomposed into water and oxygen, upon which property its great bleaching power is based. Experiments to reduce it to a solid form by refrigeration and pressure have thus far been unsuccessful. The commercial article is somewhat modified by the addition of water to prevent its ready decomposition under the influence of a warm temperature. For the same reason it is advisable to always keep it in a cool place.
LIGHT BLUE.
I. To dye this delicate color well, special care must be taken in cleaning the feathers, for which purpose only olive-oil soap of the best quality, with a little ammonia, ought to be employed. When they are perfectly clean and no more grease upon the stems, rinse them first in one or two lukewarm waters, then in cold water until the last trace of soap is removed. Then fill your basin or dyeing pan three-quarters full of cold water; put in, for a dozen feathers, one hundred and eighty grammes (about eight ounces) of raw starch in a sufficient quantity of good indigo extract to give the starch-bath the desired shade. Enter the feathers and work them gently until they are completely dyed, that is, for about fifteen or twenty minutes. Then take them out, squeeze out the starch by putting them between the fingers and thumb of your hand, and shake them before the stove, or in a well-warmed chamber until dry. While drying, beat them from time to time upon the board, or between the hands to remove the adhering starch.
II. Prepare a lukewarm bath acidulated with a few drops of sulphuric acid, so as to give a faint sour taste, to which add, according to shade, solution of methyl blue B. (Actien Gesellschaft fuer Anilin Fabrikation, Berlin). Enter the feathers and leave them in the bath until cold, or until uniformly dyed.
Note.—Some dyers use alkaline blue, which is not, however, recommendable, because alkaline baths, as above remarked, are injurious to the feathers and must be avoided as much as possible.
III. Prepare bath of lukewarm water, dissolve in it about one-half ounce tartaric acid per one quart, and add one ounce indigo carmine per quart of liquid; stir well, enter the feathers and agitate or lay down in the bath until the required shade is obtained. This color shows little fastness to light and air, which can be improved, however, by adding to the dye bath one-quarter ounce alum per quart. The shade being obtained, take up the feathers and pass, without rinsing, through raw starch milk, dry and beat as described.
Light blues, as is easy to understand, can only be dyed upon white feathers for the most delicate shades; nearly white, or developed gray feathers may be used for the shades approaching a light medium blue.