DYEING. 



which it is to be rinsed in water. This 

 process gives a pretty good black to blue 

 cloth, but only a deep brown to white : 

 the madder and tartar are supposed by 

 Lewis to be useless. 



Of dyeing Silk black. 



It is necessary to cleanse silk that is to 

 be dyed from the substance which ad- 

 heres to it, called its gum ; for though 

 raw silk takes the dye with more facility, 

 the colour is much less intense, and less 

 durable, than when the silk is scoured; 

 which is done by boiling it four or five 

 hours with a fifth of its weight of white 

 soap, after which it is beetled and care- 

 fully washed. 



After being cleansed, the silk must be 

 galled ; for which nearly three-fourths of 

 its weight of galls are boiled for three or 

 four hours, but their quantity must de- 

 pend on the kind used ; after boiling, the 

 liquor is left at rest for two hours, that 

 the galls may subside ; the silk is then 

 put into the bath, and left in it from 

 twelve to thirty-six hours ; it is then ta- 

 ken out, and washed in the river. Silk 

 is capable of combining with much of the 

 astringent matter of the galls, which at- 

 tracts the colouring matter in proportion ; 

 therefore, when what is called a heavy 

 black is required, it is allowed to remain 

 longer in the gall liquor, the galling is 

 repeated, and it is dipped in the dye 

 a greater number of times, and left in 

 it also for a considerable time. This 

 method neither improves the dye nor 

 the silk ; but is merely used to give 

 profit to the vender where silk is sold 

 by weight. 



Silk-dyers preserve the black bath for 

 silk for several years ; when its effect be- 

 comes weak, it is renewed by adding 

 more of its ingredients, and when the 

 grounds accumulate too much, they are 

 taken out. 



While the silk is preparing for dyeing 

 the bath is heated, taking care to stir it 

 occasionally, that the grounds, which fall 

 to the bottom, may not acquire too much 

 heat ; it should never be heated so as to 

 boil. Gum and solution of iron are added, 

 in proportions depending on the differ- 

 ent processes used : and when the gum 

 is dissolved, and the bath near boiling, 

 it is left to settle for about an hour. The 

 silk is then dipped into it, being in ge- 

 neral at first divided into three parts, 

 each of which is put in successively. 

 Each part is afterwards wrung gently 

 three times, and hung up in the air after 



each wringing. The action of the air 

 deepens the shade, and the wringing out 

 the liquor prepares the silk to imbibe a 

 fresh quantity. 



After this the bath is again heated, and 

 as much gum and sulphate of iron is put \ 

 in as at first. The operation is repeated 

 twice for light blacks ; but for the heavy 

 blacks three times ; and after the last the 

 silk is left in the bath for twelve hours. 

 Sixty pounds of silk are commonly dyed | 

 at one operation. 



After the dyeing is finished, the silk is 

 rinced, by turning and shaking it in a ves- 

 sel of cold water. 



Silk when dyed is extremely harsh ; to 

 soften it, a solution of four or five pounds 

 of soap to every hundred pounds of silk i 

 is poured through a cloth into a large i 

 vessel of water ; being well mixed, the 

 silk is put in, and left about a quarter < 

 of an hour, after which it is wrung out 

 and dried. 



When raw silk is dyed, the galling is 

 performed with cold liquor, to preserve - 

 its natural gum, and the elasticity which 

 it causes. If the gall liquor is weak, the 

 silk is left in it for several days ; liquor 

 that has been employed for other silk is 

 generally used, and silk which has natu- 

 rally a yellow hue is preferred. The 

 raw silk thus prepared is dyed in the 

 cold bath ; it takes the dye readily, and 

 the water in which other silk has been 

 rinced suffices to communicate it, if sul- 

 phate of iron be added. It requires more 

 or less time to lie in the rincings, accord- 

 ing to their strength : sometimes three or 

 four days are necessary, after which it is 

 washed, and beetled once or twice ; but 

 not wrung, that its elasticity may not be 

 injured. It may be dyed more speedily 

 by shaking it over in the cold bath after 

 galling, and then airing it, and repeat- 

 ing these operations a few times ; after 

 which it is to be washed and dried as 

 above. 



Macquer describes a more simple pro- 

 cess, with which they dye velvet black at 

 Genoa ; it is as follows. 



For an hundred pounds of silk, twenty 

 pounds of Aleppo galls, in powder, are 

 to be boiled an hour in a sufficient quan- 

 tity of water. The bath is then left to 

 settle till the galls have fallen to the bot- 

 tom, when they are taken out, and two 

 pounds and a half of English vitriol of 

 iron, twelve pounds of iron filings, and 

 twenty pounds of gum, are put into a 

 copper cullender with two handles, and 

 immersed in the bath ; the cullender is 

 supported by sticks, that it may not touch 



