eeping the piece tight a heavy press roller is arranged to bear on
the cloth on the full roller. When all the cloth has passed from one
roller to the other it is said to have been given "one end". The
direction of motion is now changed and the cloth sent in the opposite
direction through the jig and the piece has now received another
"end". This alternation from one roller to the other is continued as
long as is deemed necessary, much depending on the depth of colour
which is being dyed, some pale shades may only take two or three ends,
deeper shades may take more. When dyeing wool with acid colours which
are all absorbed from the dye-liquor, or the bath is exhausted, it is
a good plan to run the pieces several ends so as to ensure thorough
fixation of the dye on the cloth.

[Illustration: Fig. 16.--Dye-jiggers.]

It is not advisable in working these jigs to add the whole of the dye
to the liquor at the commencement, but only a part of it, then when
one end is given another portion of the dye may be added, such (p. 052)
portions being always in the form of solution. Adding dyes in powder
form inevitably leads to the production of colour specks on the
finished goods. The reason for thus adding the dye-stuff in portions
is that with some dyes the affinity for the fibre is so great that if
all were added at once it would be absorbed before the cloth had been
given one end, and, further, the cloth would be very deep at the front
end while it would shade off to no colour at the other end. By adding
the dye in portions this difficulty is overcome and more level shades
are obtained, but it is met with in all cases of jigger dyeing. It is
most common in dyeing wool with basic dyes like Magenta, Auramine, (p. 053)
Methyl Violet or Brilliant Green, and with acid dyes like Acid Green,
Formyl Violets, Azo Scarlet or Acid Yellow.

[Illustration: Fig. 17.--Dye-jigger in Section.]

Some attempts have been made to make jiggers automatic in their
reversing action, but they have not been successful owing to the
greatly varying conditions of length of pieces, their thickness, etc.,
which have to be dyed, and it is next to impossible to make all
allowances for such varying conditions.

[Illustration: Fig. 18.--Wince Dye Beck.]

In figure 17 is shown the jig in section, when the working of the
machine can be more easily traced.

#The Jig Wince or Wince Dye Beck.#--This dyeing machine is very largely
used, particularly in the dye