Dyeing Machinery And Dyeing Manipulations

Wool is dyed in a variety of forms, raw, loose wool; partly

manufactured fibre in the form of slubbing or sliver; spun fibres or

yarns, in hanks or skeins and in warps, and lastly in the form of

woven pieces. These different forms necessitate the employment of

different forms of machinery and different modes of handling, it is

evident to the least unobservant that it would be quite impossible to

subject slubbing or sli er to the same treatment as yarn or cloth,

otherwise the slubbing would be destroyed and rendered valueless.



In the early days all dyeing was done by hand in the simplest possible

contrivances, but during the last quarter of a century there has been

a great development in the quantity of dyeing that has been done, and

this has really necessitated the application of machinery, for hand

work could not possibly cope with the amount of dyeing now done.

Consequently there has been devised during the past two decades a

great variety of machines for dyeing every description of textile

fabrics, some have not been found a practical success for a variety of

reasons and have gone out of use, others have been successful and are

in use in dye-works.



#Hand Dyeing.#--Dyeing by hand is carried on in the simplest possible

appliances, much depends upon whether the work can be done at the

ordinary temperature or at the boil. Figure 10 shows round and oval

tubs and a rectangular vat much in use in dye-houses. These are (p. 041)

made of wood, but copper dye-vats are also made, these may be used

for all kinds of material--loose fibre, yarns or cloth. In the case of

loose fibre this is stirred about either with poles or with rakes,

care being taken to turn every part over and over and open out the

masses of fibre as much as possible in order to avoid matting or

clotting together. In the case of yarns or skeins, these are hung on

sticks resting on the edges of the tub or vat. These sticks are best

made of hickory, but ash or beech or any hard wood that can be worked

smooth and which does not swell much when treated with water may be

used. The usual method of working is to hang the skein on the stick,

spreading it out as much as possible, then immerse the yarn in the

liquor, lift it up and down two or three times to fully wet out the

yarn, then turn the yarn over on the stick and repeat the dipping

processes, then allow to steep in the dye-liquor. This is done with

all the batch of yarn that is to be dyed at a time. When all the yarn

has been entered into the dye-bath, the first stickful is lifted out,

the yarn turned over and re-entered in the dye-liquor; this operation

is carried out with all the sticks of yarn until the wool has become

dyed of the required depth. In the case of long rectangular vats it is

customary for two men, one on each side of the vat, to turn the yarns,

each man taking charge of the yarn which is nearest to him.



Woven goods may be dyed in the tub or vat, the pieces being drawn in

and out by poles, but the results are not altogether satisfactory, (p. 042)

and it is preferable to use machines for dyeing piece goods.



Plain tubs or vats, such as those shown in figure 10, are used for

dyeing and otherwise treating goods in the cold, or at a lukewarm

heat, when the supply of hot water can be drawn from a separate

boiler. When, however, it is necessary to work at the boil, then the

vat must be fitted with a steam coil. This is best laid along the

bottom in a serpentine form. Above the pipe should be an open

lattice-work bottom, which, while it permits the free circulation of

boiling water in the vat, prevents the material being dyed from coming

in contact with the steam pipe. This is important if uniform shades

are to be dyed, for any excessive heating of any portion of the bath

leads to stains being produced on the material in that part of the

bath. Figure 11 shows a vat fitted with a steam pipe. That portion (p. 043)

of the steam pipe which passes down at the end of the vat is in a

small compartment boxed off from the main body of the vat, so that no

part of the material which is being dyed can come in contact with it.

A closed steam coil will, on the whole, give the best results, as then

no weakening of the dye-liquor can take place through dilution by the

condensation of the steam. Many dye-vats are, however, fitted with

perforated, or as they are called, open steam coils, in which case

there is, perhaps, better circulation of the liquor in the dye-vat,

but as some of the steam must condense there is a little dilution of

it.