498

DYEING AND CALICO PRINTING.

water are added to dilute the mixture. After this mixture has been printedon, the tissue' is exposed for twenty-four hours to air, and is next passedthrough a bath of bichromate, consisting of 5 grms. of the salt per litre ofwater, and kept at a temperature of 94°, this operation being carried on in atank provided with rollers, so that the tissue is only in adtual contadt with theliquid for about two minutes ; the goods are next washed for half an hour inthe washing machine in cold water.

2. Print on a decodtion of catechu, leaving out the iron preparation, andotherwise proceeding as above diredted.

3. Print on the following Nankeen mordant,* consisting of—Copperas,2 kilos.; acetate of lead, i'5 kilos.; water, 2 litres. After the separation ofthe sulphate of lead there is added for every 2 litres of this preparationi'25 kilos, of British gum; the mixture then forms the standard colour, which,according to requirements, is diluted with from 7 to 45 litres of British gumsolution. After having printed this mordant on the pieces they are aged fortwenty-four hours, and next passed through a silicate of soda bath, and, afterhaving been washed, the following catechu mixture is used as dye (the mixtureto serve for 50 metres):—

Water.150 litres.

Decodtion of catechu, containing 180 grms. to the litre 3 „

The temperature is gradually raised from ig° to 8o°; after passing throughthe bichromate the goods are washed in the machine and dried.

4. Print on a red liquor, which is fixed as there diredted, dye in cutch, andbichromatise.

For so-called mode grounds the following processes are employed;—

1. A mixture of cutch and pyrolignite of iron is printed on, and the tissue

next passed through a bichromate bath at the temperature of 56°.

2. The above-named Nankeen mordant is printed on first, and the fabric

next dyed in cutch also, as above specified, but the bichromate bath isnot employed.

3. A mixture of catechu decodtion and Nankeen mordant is printed on first,

after which the fabric is aged for twenty-four hours, then exposed in asteam chest at a pressure of 30 lbs. to the square inch (2 atmospheres)for half an hour, and, lastly, washed and dried.

The same processes as those just specified are also employed for silk andwool, but the use of catechu for these animal fibres is limited to being anadjundt in some kinds of black dyeing. The browns which it yields are not sodesirable as those which can be obtained from a mixture of other colouringmatters and mordants.

Catechu is largely used in woollen printing (flannels and linseys) for ob-taining dark shades of drab, of a red or brownish tinge, in combination with

* The name of Nankeen colour is usually given to the shade of buff obtained from ironsalts ; in piece dyeing the cloth is run through copperas liquor, and then through lime-water;for lighter shades nitrate of iron is preferable ; the colour may be softened both in appearanceand to the feel by finally working in warm soap-suds; annatto gives yellower Nankeen shades,which may be combined with chrome yellow. Nankeen has obtained its name from theChinese city Nankin, whence a peculiar buff-coloured silk and cotton were first importedinto Europe. The Nankeen dyes with cutch are fast, but a great many inferior imitationsexist, and have been treated of in our foregoing pages under various headings.