to
be dyed a dark shade the treatment is less elaborate.

[Sidenote: Singeing and Shearing]

If the cloth is to be printed for calicoes, before bleaching it is
singed by passing through gas flames or over a red hot plate and then
sheared in a shearing machine constructed somewhat on the principle of
the lawn mower, the cloth being run close to the rapidly revolving
knives.

Although cotton is usually dyed in the piece, it may be dyed in the form
of yarn, as for ginghams, and sometimes before being woven, in the loose
state.

[Sidenote: Mordant Colors]

Cotton is more difficult to dye than wool or silk. Although there are
now what are called "direct" cotton colors, the usual process is to
first treat the cotton goods with a "mordant"--various salts of
aluminum, chromium, iron, tin and copper, fixing these on the fiber by
means of tannin or alkali. The mordanted cloth is then entered into the
dye bath and boiled for an hour or longer, until the desired shade is
obtained or the dye bath exhausted. The salts of aluminum are used as
mordants for the lighter shades, the salts of chromium for the medium
shades, and iron for the dark shades. In general, chromium mordants give
the fastest dyes.

[Sidenote: Aniline Dyes]

The discovery of the so-called aniline dyes has greatly increased the
variety of colors available. Although some of the first aniline dyes to
be made were not fast to washing or to light and they thus received a
bad reputation, they are now to be obtained which compare favorably in
fastness with the natural dye stuffs such as cochineal, madder, etc.,
provided sufficient time and care are given to dyeing. The chief trouble
is that in the endeavor to furnish cheap goods, processes are hurried
and results are unsatisfactory.

[Sidenote: Home Dyeing]

Home dyeing is practically confined to the use of direct aniline colors.
These are put up in small quantities and sold in many places. Directions
for their use are given on the packages. The chief precautions are to
have the goods perfectly clean and thoroughly wet before entering into
the dye bath (this is by no means as easy as one might think), and to
keep the goods in motion while dyeing so as to prevent unevenness of
shade. Wool and silk dyes cannot be used for cotton and linen, nor the
reverse. Of course cloth already colored cannot be dyed a lighter shade
of the same color and the original shade must be very light to enable
one to change the color,