epends upon the efficiency with which the (p. 072)
mordanting has been carried out. If this is at all unevenly done then
no amount of care in the succeeding dyeing process will lead to the
development of an even dyeing. After the mordanting is finished the
goods should be rinsed with water, but it is not necessary to dry
them.

The next stage in the process is the actual dyeing operations, which
is done by immersing the mordanted wool in a bath of the dye-stuff or
mixture of dye-stuffs.

The fundamental principle is to bring about the combination between
the colouring principle of the dye-stuff and the metallic oxide which
has been deposited on the wool in the previous mordanting process. As
neither of these bodies, however, is very energetic it follows that
the action must be a slow one, and, therefore, time is a highly
important factor in the dyeing of wool by the mordanting process. The
combination between the dye-stuff and the mordant is influenced also
by temperature, and is most active at the boiling point of water. It
is, therefore, needful to conduct this operation at that temperature,
but it would be a wrong way to introduce the mordanted material into a
boiling bath of the dye-stuff; nothing would conduce to uneven dyeing
so much as that course. The best method of working, which, moreover,
is most particularly applicable to the series of Alizarine dye-stuffs,
is to enter the goods in a cold bath of the dye-stuff, and to work
them for a short time to get them thoroughly impregnated, a condition
which is essential if even dyeing is the goal aimed at, then to raise
the temperature of the bath gradually to the boil, the goods being in
the meantime well worked. The dyeing is continued for from one to one
and a half hours at the boil.

It is important in dyeing by this process, especially when using
Alizarine, to keep the temperature of the bath as uniform as possible,
and the goods well worked. Alizarine, and some other members of (p. 073)
this class, are rather sensitive to heat, and if a dye-vat be hot at
the bottom and cold at the top uneven dyeing is sure to be the result;
this is due to the greater affinity of the Alizarine for the mordant
at the high than at the low temperature, and thus more is fixed on to
the wool. The remedy for this is to so construct the heating
arrangements of the vat that the temperature shall be as uniform as
possible, while the goods should be kept continually turned over, and