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.