The Dyer's Guide. Chapter VI. On Dyeing Cotton And Silk. Observations on silk. On ungumming and boiling silk.

The Dyer's Guide
Being a Compendium of the Art of Dyeing
Linen, Cotton, Silk, Wool, Muslin, Dresses, Furniture, &c. &c.

With The Method of
Scouring Wool, Bleaching Cotton, &c.
Directions for Ungumming Silk, And For Whitening And Sulphuring Silk And Wool.
And Also
An Inttroductory Epitome of The Leading Facts in Chemistry, As Connected With The Art of Dyeing.

By Thomas Packer,
Dyer and Practical Chemist.

"Cet arte est un des plus utiles et des plus merveilleux qu'on connoisse."
- Chaptal.

"There is no art which depends so much on chemistry as dyeing."
- Garnett.

Second Edition,
Corrected and Materially Improved.

Printed for Sherwood, Gilbert, And Piper,

Observations on silk.

Silk, as it is obtained from the cocoons of the worm, is generally of an orange or yellow colour, more or less dark; in the South of France it is generally very dark: its natural shade is unfavourable to almost all other colours. It is also imbued with a kind of varnish or gum, which makes it stiff and hard; this stiffness is improper in the fabrication of most silk stuff, it is therefore ungummed, as it is called, by the following processes.

On ungumming and boiling silk.

Observe, that throughout the following processes for silk white soap is directed to be used; and, generally speaking, we believe it will be found the best, more especially for the more delicate operations. Yet Mr. M'Kernan, in his process for ungumming silk, directs yellow soap and soft soap in equal parts, and of the same weight as the silk to be used: he adds, however, that different sorts of silk require more or less soap; the best rule he finds, nevertheless, is the same weight of soap as of silk: and he says also, that yellow soap and soft soap of the best quality he finds the best for this purpose.

The silk is divided into hanks, each hank is tied with a string, several of these are tied together (a handful of them) by putting a piece of string through each separate skein, and tying the piece of string in a long tie to slip easily when they are wanted to be untied.

A liquor is prepared of thirty pounds of white soap to a hundred pounds of silk; the soap is cut into small pieces and boiled in water, when it is dissolved the fire is damped.

While the liquor is preparing the skeins of silk are put on rods; as soon as the soap liquor becomes a little below boiling heat (for it should not boil, as boiling would tangle the silk) the silk is to be put into it in an oblong copper, being nearly full; it is to remain in the liquor till its gummy matter has left it, which will be seen by its whiteness and flexibility. It is then turned end for end on the rods, that the part above the liquor may undergo the same operation. As soon as this is accomplished the silk is taken out of the copper, the hanks which were first turned being soonest done.

The hanks are now to be taken from the rods to the peg, disentangled, and nine or ten of them put on one cord, this cord passing through the string that tied each hank. When the whole is corded it is put into pockets of fcoarse strong white linen fifteen inches wide and five feet long, closed at each end and on one side; when the silk is put in, the pocket is sewed all along the other side with packthread, and fastened with a knot; four pockets will hold the whole hundred pounds.

The pockets being thus ready another liquor is prepared like the first. When ready, and the boiling checked with cold water, the pockets are put in and boiled well for a quarter of an hour, checking with cold water in order to prevent its boiling over; it is necessary also to turn the bags about often with a pole, or rather let two persons have a pole each for this purpose. This operation is called boiling.

In addition to the processes of boiling with soap, as above directed, Mr. M'Kernwi recommends that the silk should be winched through a copper of water at the heat of 160°', having two pounds of soda (barilla) dissolved in it, then winch or wash in water, and wring and dry.

In the boiling of silks for common colours twenty pounds of soap will do for a hundred weight of silk; but, as in this case, the silk is not ungummed, it should boil for three hours and a half, adding water to supply the evaporation.

The silks intended for the greatest degree of white, either to remain white, or for the fabrication of white stuff, are boiled twice in soap and water; those that are to be dyed of different colours are boiled but once, and with a smaller quantity of soap, because the little remaining redness is by no means prejudicial to many colours. Different quantities of soap are, however, necessary for different colours.

Silk designed for blue, iron grey, brimstone, or any other colour requiring a very white ground, should be done according to the preceding process, and have thirty pounds of soap.

When the silk is boiled it is taken out of the copper by two men with poles, and placed in a clean barrow; they are then taken to a long shallow trough, from which the water may run away, the pockets are opened, and the silks examined; such as have yellow or lemon colour spots remaining are boiled again for some time, till the spots are removed. After unpocketing, the whole is dressed on the pegs.

Silk loses from twenty-five to twenty-eight per cent, of its weight in ungumming and whitening. The bags of silk should never be suffered to lie long together before they are emptied after being boiled, as their doing so would make the silk hard.

White silk, as before observed, is distinguished into five principal shades, namely, China white, India white, thread or milk white, silver white, and azure white.

The three first are prepared and boiled as has already been shewn. Silver and azure white in the preparation or ungumming thus: take fine powdered indigo, put it into water boiling hot, when settled the liquor is called azure.

To azure the silk it is taken from the ungumming copper after it is dressed and put into a trough of water; after it is worked, drained, and again dressed, it is ready for the [whitening].

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