Observations on CRIMSON and SCARLET upon silk.
Crimson upon silk is produced at Norwich, London, and many other places, by using a much larger quantity of cochineal than that which is directed by Macquer: for in some cases, as much as a guinea a pound, has, it is said, been paid for dyeing silk crimson at Norwich. Archil has been used, likewise, in crimson, and the time of boiling is not so long. In some shades a little of the composition and tartar may be admitted, but in a small degree. It should be stated, however, that scarlet upon silk, is often done by annatto and safflower.
Observe, that although we have given the preceding processes for crimson and scarlet, yet many others might be mentioned. What has been said in regard to dyeing scarlet on woollen, (page 85.) should also be carefully attended to, particularly relative to the conversion of scarlet into crimson by alum, soap, and the alkalies. And though we have given directions for the preparation of a nitro-muriate of tin, yet pure
Muriate of tin
is now very often used for dyeing silk red. Mr. M'Kernan, gives us the following process for preparing it:
Take of fine muriatic acid, of the specific gravity of 1.120, two quarts; add by degrees, one ounce at a time, of feathered tin, for twenty-four hours. Put the vessel in a sand heat and bring it gently to boil, observing to add more tin as that in the acid becomes dissolved. There should be some tin left undissolved when the liquor is cold, thus indicating that the acid is perfectly neutralized by the tin. Bottle for use.
On dyeing silk GREEN.
This colour is composed of blue and yellow. It is with difficulty produced on silk, because the blue vat is liable to spot and give a party colour, an inconvenience to which green is more liable than blue, and more perceptible. The boiling of silk for greens is the same as for common colours.
The silk being alumed as usual rather strongly, is washed off and divided on the sticks into small hanks of about four or five ounces, that it may be equally and easily managed in the working, from the yellow to green, in the blueing from the blue vat.
Weld is then boiled as stated in the article concerning yellow; when boiled, a liquor of it is prepared strong enough to give a lemon ground; the silk is then turned with all the expedition, care, and caution possible, that it may be even. When it appears full enough, some of the threads are to be separated and dipped in the vat, to determine this. If not full enough, more of the weld liquor must be added to the dye bath, and the silk returned and tried again, and so on; when the colour is right, the silk is washed off and beetled. It is then wrung and formed into hanks, and dipped skein by skein in the blue vat, the same as the blue and the purple should be; it must be wrung with equal care and dispatch.