Goods, mordanted with alumina and dyed with alizarin for reds
up to saturation, never reach the brown tone given by fleur or garancin.
This tone is due in great part to the presence of fawn colored matters,
which the cleanings and soapings served to destroy or remove. The same
operations have also another end--to transform the purpurin into its
hydrate, which is brighter and more solid. The shade, in a word, loses
in depth and gains in brightness. With alizarins for reds, the case is
quite different; they contain no impurities to remove and no bodies
which may gain brightness in consequence of chemical changes under the
influence of the clearings and soapings. These have only one result, in
addition to the formation of a lake of fatty acid, that is to make the
shades lose in intensity. The method of subjecting reds got up with
alizarin to the same treatment as madder-reds was faulty.
There appeared next a method of dyeing bases upon different
principles. The work of M. Schuetzenberger (1864) speaks of the use of
sulpho-conjugated fatty acids for the fixation of aniline colors. In
England, for a number of years, dyed-reds had been padded in soap-baths
and afterwards steamed to brighten the red. In 1867, Braun and Cordier,
of Rouen, exhibited Turkey reds dyed in five days. The pieces were
passed through aluminate of soda at 18 deg. B., then through ammonium
chloride, washed, dyed with garancin, taken through an oil-bath, dried
and steamed for an hour, and were finally cleared in the ordinary manner
for Turkey-reds.
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