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Gustav Stickley (ed.) / The craftsman
Vol. XIV, Number 4 (July 1908)

Pellew, Charles E.
General description and classification of the artificial dyestuffs: number II,   pp. 447-450 PDF (1.5 MB)


Page 450


CLASSIFICATION OF COAL TAR COLORS
in it, and also be made slightly alkaline
with soda ash. The cotton, thoroughly
wetted, is then immersed, and gradually
warmed, and then a considerable quan-
tity of salt-or, better, of Glauber salt-
added, and the bath brought up to a
boil, and kept boiling for half to three-
quarters of an hour. The goods are
then taken out, rinsed slightly in water,
and then dried. The reason usually
given for adding salt or Glauber salt
to the dyebath is that its presence
makes the dyestuff less soluble in the
liquid, and hence more ready to deposit
on and adhere to the fiber. On account
of this practice these Direct Cotton Dye-
stuffs are often called the "Salt Colors."
  For Mercerized Cotton.-This has
such a strong affinity for the color that
the amount of dyestuff and of salt may
be much diminished, and the bath not
heated hotter than 14o0 or I5o° F. It
is well, also, to add a litle Turkey Red
oil to the bath before immersing the
goods.
  For Linen.-Linen is dyed the same
as cotton, excepting that the amount of
salt is diminished, and some Turkey
Red oil is added, to make the color go
on more slowly, and so penetrate the
fiber better.
  For Wool and Silk.-These dyes are
not used on animal fibers as much as the
Acid Dyes. They will, however, dye
wool in a hot bath containing a consid-
erable amount of salt or Glauber salt,
and slightly acidified with acetic acid.
After dyeing, the silk is rinsed in water
slightly acidulated with acetic acid.
  Colors Produced.-These direct cot-
ton, or salt dyes, give as a rule very
bright, clear, pretty shades. They are
easy of application and dye evenly.
   On cotton the colors are not, as a
rule, fast to light, and are apt to bleed
when boiled with white goods. On
wool and silk the colors, while not, in
most cases, fast to light, are very fast
to washing.
450
  Selected  Colors.-The dyes men-
tioned in the following table are all de-
cidedly fast to light, far more so than
most of the class:
Badische-Oxamine Blue B; Cotton
  Yellow G; Oxamine Fast Red F.
Cassella-Diamine Fast Blue FFG; Di-
  amine Fast Yellow FF; Diamine Fast
  Red F; Diamine Fast Brown R; Di-
  amine Fast Grey G.
Elberfeld-Brilliant Azurine 5G; Chrys-
  ophenine G; Benzo Fast Scarlet 4BS.
Kalle-Direct Blue B conc (concen-
  trated) ; Naphthamine Yellow NN
  conc; Naphthamine Fast Red H;
  Naphthamine Brown HR.
Metz-Direct Blue io8; Oxydianil Yel-
  low 0; Direct Scarlet B.
  After Treatment.-To increase the
fastness to washing and, to some ex-
tent, to light, of these dyes, it is cus-
tomary to after-treat them, especially
when dyed on cotton. By the process
known as "Diazotizing and Developing"
these can be made exceedingly fast.
The method, however, is hardly avail-
able for any one not a skilled dyer.
  It is also possible, by "topping"
fabrics dyed with these colors with
Basic dyes, to get shades quite fast to
washing. Only a few, however, of the
Basic colors, like "Methylene Blue" or
"Methylene Violet," are any faster to
light than the common run of the direct
cotton colors themselves.
  The simplest method of after-treating
is to boil the dyed goods for fifteen or
twenty minutes in a bath containing a
little copper sulphate, IY2 or 2 per cent.,
and sometimes the same amount of bi-
chromate of potash, acidified with a
little acetic acid. This, in general, fixes
the color so that it will not wash out nor
bleed, and makes it faster to light at the
same time,
  This after-treatment is not necessary
for wool and silk dyed with the selected
colors, but, in special cases, will be
found valuable for cotton.


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