Both these techniques are widely used in Saris and dress material in India
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Carbonized Polyester Printing
In the carbonization process the cellulosic component of the polyester/ cellulosic blend is dissolved by treating the fabric with 70% sulfuric acid along with small quantities of sulphamic- acid and urea, with the result one gets 100% polyester fabric with very soft handle. It is advisable to use polyester rich blends to avoid the problem of slippage. To produce the carbonized polyester prints initially the cloth is printed with the disperse dyes.
Disperse dye - x parts
Ammonium sulphate (or citric acid) - 3-5 parts
Sodium chlorate - 1 -2 parts
Thickening (guar gum) 600-700 parts
Water - y parts
Total - 1000 parts
Print, dry and fix by steaming at 130C for 30-45 min. The fabric is then be washed, reduction cleared
and carbonized. The carbonization process can be carried out either by a batch process in a jigger or by a pad-batch method. In the jigger the fabrics are treated for 30-40 min ( 2-4ends) at room temperature. The fabric is then washed and neutralized. A mild bleaching treatment may be given to improve the whiteness of the prints.
Brasso or Cut-out Style
This style involves localised dissolution of the cellulosic component at printed portion by printing the polyester /cellulosic fabric with acid liberating salts. The fabric is initially printed with:
Aluminium Sulphate - 200 parts
Water. - 100-200 parts
Citric acid - 20-30 parts
Wetting Agent(acid stable) - 10-20 parts
Glycerine - 50-70 parts
British gum (1: 1) - x parts
Total - 1000 parts
Print, dry, bake at 130-145'C for 3 to 5 min.
The goods are then thoroughly washed a winch to remove the
degraded cellulosic component. a winch to remove the degraded cellulosic component. Bleaching may be carried out to get better whiteness.
Cellulase enzyme treatment can also be done to get this effect, as it hydrolizes the cotton componetn. In the case of cotton rich blends, the traces of cellulosic part remain on material and therefore more severe enzymatic treatments are required. The acidic cellulase enzyme is the best suitable for this application. The same principle is used in brasso style of printing in which cellulosic portion is removed from the polyester-cotton blend material after printing. the advantages of carbonization using cellulase enzymes are: 1. The process is non-corrosive and non hazardous 2. Less wear and trea of machines 3. Eco friendly process 4. No separate curing is required as in conventional brasso printing. v. No adverse effect on the print color and feel of the fabric.