11)

EXPERIMENTAL DYEING AND COMPARATIVE DYE TESTING.

Every dyer ought to be able to make experiments in the mordanting and
dyeing of textile fibres for the purpose of ascertaining the best
methods of applying mordants or dye-stuffs, the best methods of
obtaining any desired shade, and for the purpose of making comparative
tests of dyes or mordanting materials with the object of determining
their strength and value. This is not by any means difficult, nor does
it involve the use of any expensive apparatus, so that a dyer need not
hesitate to set up a small dyeing laboratory for fear of the expense
which it might entail.

In order to carry out the work indicated above there will be required
several pieces of apparatus. First a small chemical balance; one that
will carry 50 grammes in each pan is quite large enough, and such a
one, quite accurate enough for this work, can be bought for 25s. to
30s., while if the dyer be too poor even for this a cheap pair of
apothecaries' scales might be used. It is advisable to procure a set
of gramme weights and to get accustomed to them, which is not by any
means difficult.

In using the balance always put the substance to be weighed on the
left-hand pan and the weights on the right-hand pan. Never put
chemicals of any kind direct on the pan, but weigh them in a
watch-glass, small porcelain basin, or glass beaker (which has first
been weighed), according to the nature of the material which is being
weighed. The sets of weights are always fitted into a block or (p. 212)
box, and every time they are used they should be put back into their
proper place.

The experimenter will find it convenient to provide himself with a few
small porcelain basins, glass beakers, cubic centimetre measures, two
or three 200 c.c. flasks with a mark on the neck, a few pipettes of
various sizes, 10 c.c., 20 c.c., 25 c.c.

The most important feature is the dyeing apparatus. Where only a
single dye test is to be made a small copper or enamelled iron
saucepan, such as can be bought at any ironmongers may be used; this
may conveniently be heated by a gas-boiling burner, such as can also
be bought at an ironmongers or plumbers for 2s.

[Illustration: Fig. 33.--Experimental Dye-bath.]

It is, however, advisable to have means whereby several dyeing
experiments can be made at one time and under precisely the same
conditions, and this cannot be done by using the simple means noted
above.

To be able