PRINTING ON CALICO. 



yet having in itfelf no affinity with the vegetable vHth 

 which the decoftion is impregnated, the whole of the 

 colouring matter will be eafily removed by expofure to the 

 air, and the ground of the piece reftored to its original 

 whitenefs ; while thofe parts to which the mordant was 

 applied, will retain and fix the colours in a way which will 

 be more fully explained hereafter. 



Formerly all calico-printers were bleachers ; but in the 

 neighbourhood of London thefe are feparate and diftinft 

 trades, and the printer either purchafes bleached goods for 

 printing on his own private account, or receives the cloth 

 from his cuftomers in a white ftate ; and, when printed, 

 he returns the identical pieces, and is paid fo much^fr yard, 

 according to the number of colours, for printing them. 



In our opinion every printer fhould bleach his own 

 goods, for it is impoffible always to rely with confidence 

 on the care of thofe who bleach for hire ; and every printer 

 knows that good bleaching is abfolutely a neceffary pre- 

 liminary in the produftion of good printing. Indeed, this 

 is now pretty generally acknowledged in the north of 

 England ; for mod of the opulent houfes in Lancaihire and 

 in Scotland, which produce fine work, are bleachers as well 

 as printers. 



Oxymuriate of lime is the agent generally employed in 

 bleaching ; but it appears to us that fome other article 

 might be introduced with advantage. For, as the goods 

 are vvafhed in diluted fulphuric acid when they are taken from 

 the ox)muriate of lime, a fulphate of lime is always formed, 

 which becomes fixed in the fabric, and, afting as a mordant 

 when the pieces come into the madder-copper, occafions an 

 indelible ftain, which in very fine goods often impairs their 

 beauty. If oxymuriate of foda were employed, the ful- 

 phuric acid would form a foluble fait with the foda, eafily 

 removable by walhing. 



No people have taken more pains to excel in bleaching 

 than the Irilb, and their credit is eftablifhed accordingly. 

 The German linen, we beUeve, is generally better than 

 theirs ; but the Irifli has always the preference in foreign 

 markets, owing to their fuperiority in bleaching and finifhing. 



A very minute account of the various proceffes in bleach- 

 ing has been already given in our 4th vol. part ii. under 

 the article Bleaching ; which fee. 



By whatever means the bleaching is performed, the 

 printer commences his part of the bufinefs in the following 

 manner. 



The goods are firft drejfed by fingeing off the whole of 

 the nap which is attached to them. This is effefted by the 

 following contrivance : — Ten pieces are generally wired 

 together, and wound upon a roller, from whence they are 

 paffed over a hot iron, nearlv in the form of half a cylinder, 

 and received upon another roUer ; from thence they are 

 returned to the iron, which is ftill kept red, or nearly at a 

 white heat. The ufe of repeating this procefs is to remove 

 the nap more effeftually than it would be done by paffing 

 it only once over. 



The next operation is that of Jleeping, which confifts 

 merely in foaking the pieces for twenty-four hours in a 

 vefTel of weak alkaline ley, at a temperature of about 100'. 

 Thefe operations of fingeing and fteeping are going on at 

 one and the fame time, which effeftually prevent any accident 

 that might otherwife arife from the effects of the hot iron. 



The goods are then boiled or elfe bowked in a folution 

 of potafh (fome workmen prefer to have this alkali in a 

 pure cauftic ftate) ; they are then well clcanfedby thorough 

 wafhing in wafh-wheels, or in flocks, to enfure their being 

 entirely diverted of the alkali. The intention of thus 

 treating them with potafh, is to remove any greafe or im- 



purity that may be attached to them, which would other- 

 wife endanger the evennefs and uniformity of the colours. 

 This procefs is called ajhing. 



By fome obfervant calico-printers it has been imagined, 

 that the rendering of the ley cauftic is apt to impair the 

 texture of the cloth ; and we doubt not but that this has 

 often been the cafe. Under the eye of the mafter, however, 

 we are fure that it might be employed with advantage and 

 fafety. 



It may be remarked, that in weaving calicoes the work- 

 man generally greafes the reeds, in order to make them 

 move eafier. Tallow is alfo employed for drefiing the warp, 

 and this has a baneful effeft on all goods which are de- 

 figned for printing. Wherever this greafe is in the cloth, 

 it becomes fixed by the operation of fingeing ; and if it be 

 not taken out before bleaching, it will not come out after- 

 wards by the ufual procefs of afhing and fouring ; for, 

 when the pieces are fubmitted to a blue vat to be dyed of 

 a uniform felf-colour, all thofe greafy places will be found 

 to have taken the dye in a very imperfecl manner. If the 

 calico-manufafturers themfelves would make a point of pre- 

 paring the oleaginous matter for the weavers, and would 

 furnifti them with nothing but pure vegetable oils, fuch as 

 thofe of rape, linfeed, &c., it is very likely that thefe in- 

 conveniences would not occur ; for the ftain from -vegetable 

 is not fo indelible as that from animal oil. To cleanfe fuch 

 goods, various expedients have been adopted, but we ap- 

 prehend nothing but a folution of cauftic alkali can be 

 depended upon. To prove the effeft of any method which 

 may be tried, it is a good way to run the pieces through 

 water, and then to pafs them from the water fo gradually 

 over a roller, as to give the fuperintendant an opportunity 

 of examining every inch of the furface ; and if any part 

 remains greafy, it will be feen at once, for that part will 

 continue dry, while all the reft of the cloth is wet. 



There is another way in which the goodnefs of bleaching 

 might be proved. Let a few of the fufpeCted pieces be run 

 once or twice tlirough a madder-copper, at the temperature 

 of about 180°. This Avill inevitably mark any part that 

 may be imperfectly bleached ; whereas, if the operation has 

 been properly performed, they will come out fo little ilained, 

 that an intelligent workman, who has been ufed to a madder- 

 copper, will at once be fatisfied that they contain no im- 

 purity that can form a permanent mordant. 



The next procefs is one with diluted fulphuric acid. A 

 quantity of foft water having been poured into a leaden 

 veffel, oil of vitriol is gradually added to it, in the propor- 

 tion of about twenty pounds of oil of vitriol to every hun- 

 dred gallons of water, which by weight is in the proportion 

 of about one to forty. 



When this mixture has been well ftirred, it is ready for 

 ufe. Sometimes it is employed in this ftate, at others it is 

 heated to 90° or upwards of Fahrenheit, according to the 

 nature of the work to be done, and the goods are iinmerfed 

 in it. They are not fuffered to lie in tliis folution, but axe 

 wound by means of a winch over a wooden cylinder, that 

 every part of the cloth may be immerfed in the fluid, and 

 expofed alternately to the aftion of the atmofpliere. 



This operation is generally continued for about twenty 

 mmutes, and is defigned to remove any iron-moulds or 

 other ftains which the cloth may have acquired. It has alfo 

 the effeft of neutralizing any portion of potafti that may 

 have been left in contaft with the cloth. The procefs is 

 called youWnj. 



After this operation it is neceff^- to walh the goods 



thoroughlv, that no part of the acid may be left in them 



to iniure their texture, and this is beft effeded by means of 



■* 4H 2 



the 



