646 CA UCO-PRINTING 



No. 84. China blue gum. Qum-Senogal solution nt 3 Ibs. per gallon, containing 

 4 oz. copperas per gallon. 



Colours are made by reducing the standard blue with the gum, according to the 

 pattern and strength required. For instance, for two blues of medium shades : 



No. 85. Strong Blue. 1 volume standard, 2 volumes gum. 



No. 86. Pale Blue. 1 volume standard, 10 volumes gum. 



After printing, age one night, and raise as follows : Two vats similar to indigo 

 rate are set. No. 1. 1,000 gallons water, 500 Ibs. slaked and dry lime. No. 2. So- 

 lution of copperas at 5 T. In each vat is lowered a frame, which is provided with 

 rollers at top and bottom, and in addition, has a pair of bushes at each side of the 

 frame, just above the surface of the liquor, in which are put beams, on which the 

 pieces are wound alternately ; the bearings of the beams being just above the 

 surface of the liquor, allow the roll of pieces to be always half in and half out of the 

 liquor. The course of proceeding is this : A beam containing two or three pieces 

 stitched end to end is placed on a small frame at one side of vat No. 1, and by means 

 of a cord previously threaded through the rollers in the vat, the pieces are slowly 

 wound through the vat and on to a beam placed in the bearings at the opposite side 

 of the vat, by means of a winch handle fitted on this beam ; when the pieces have 

 thus passed through vat No. 1, which is kept in a milky state all the time, the beam 

 is lifted out and transferred to one of the pair of bearings in vat No. 2 ; the pieces 

 are wound through this vat in the same manner ; after this vat, they are removed to 

 No. 1 vat, and worked through ; this alternate limeing and copperasing is continued 

 till the pieces have been 4 times through each vat ; then detach and wince in water ; 

 then put into sulphuric sours at 10 T., immersing completely in the liquor till tho 

 whites appear quite clear; then wash well, soap in a beck at 120 F. a quarter of an 

 hour with Ib. soap per piece ; wash again and sour in sulphuric sours at 1 T. at 

 1 10 F. ; wash well and dry. 



The various phenomena which occur in the dipping of China blues are not difficult 

 of explanation with the lights of modern chemistry. Wo have, on the one hand, 

 indigo and sulphate of iron alternately applied to the cloth ; by dipping it into the 

 lime, the blue is deoxidised, because a film of the sulphate of iron is decomposed, and 

 protoxide of iron comes forth to seize the oxygen of the indigo, to make it yellow- 

 green, and soluble at the same time in lime-water. Then, it penetrates into the heart 

 of the fibres, and, on exposure to air, absorbs oxygen, so as to become insoluble 

 and fixed within their pores. On dipping the calico into the second vat of sulphate 

 of iron, a layer of oxide is formed upon its whole surface, which oxide exercises an 

 action only upon those parts that are covered with indigo, and deoxidises a portion of 

 it ; thus rendering a second dose soluble by the intervention of the second dip in the 

 lime-bath. Hence we see that while these alternate transitions go on, the same 

 series of deoxidisement, solution, and re-oxidisement recurs : causing a progressively 

 increasing fixation of indigo within tho fibres of the cotton. 



Other indigo styles are dipped greens, blue with white discharge. 



Sipped Greens. There are 4 vats similar to indigo vats in a row, set with 



First : (No. 5.) Light blue Vat for Greens. 1,000 gallons water, 25 Ibs. indigo, 45 Ibs. 

 copperas, 65 Ibs. lime, dry slaked, 17 Ibs. caustic soda, 24 T. ; raked up 2 days, 

 and settled clear. 



Second: (No. 6.) Yellow Vat for Greens. 1,000 gallons water, 250 Ibs. brown acetate 

 of lead, 130 Ibs. dry slaked lime ; rake up till dissolved, and lot settle clear. 



Third : (No. 7.) Filled with water only. 



Fourth : (No. 8.) Set with bichromate' of potash at 4 T. 



Each of these vats is mounted with a frame with rollers top and bottom ; the 

 pieces to be dipped are stretched end to end, and a length of cord being threaded 

 through all the vats and fastened to a drawing roller at the end of tho fourth, the pieces 

 are drawn slowly through between the first and second; tho cloth is made to travel 

 several yards so as to ensure oxidation of the indigo before going into the lead vat ; 

 after leaving the fourth, they are detached, winced, and washed well. 



For dipped greens, either white cloth is printed in patterns, as spots, &c., with mild 

 paste, Nos. 69, 70 ; or a pattern previously printed in madder colours and dyed, &c. 

 is covered up with mild paste by block ; the cloth being now dipped green, tho pattern 

 or spots are reserved or untouched by the green : a very good effect is produced by 

 dipping tho Burgundy and acid No. 4, green, when the Burgundy part comes out 

 a beautiful chocolate, and tho white part green. 



Acid Discharge on Blue. A blue and white style, but which permits the most deli- 

 cate pattern to be printed, which is not the case with the ordinary blue and white 

 style. The cloth is first dipped a medium shade of blue, washed and dried, then 

 padded in bichromate of potash at 6 T. and carefully dried in the shade, without 

 artificial heat, and printed in the following colour : 



