CALICO PRINTING. 197 



The process of calico-printing consists in impreg- 

 nating those parts of the cloth which are to receive 

 the coloured pattern with a mordant, and then dye- 

 ing the cloth by the usual methods. The dye is 

 firmly fixed to that part only where the mordant 

 has been applied ; and, although the whole cloth 

 has received the tint, yet the colour will be easily 

 discharged from the unmordanted parts by washing, 

 and exposing on the grass to the sun and air for 

 some days with the wrong side uppermost. Thus, 

 suppose a pattern had been applied to white cloth 

 with a solution of acetite ofalumine, and that then, 

 the whole was dyed with madder ; when taken out 

 of the dye-vat the whole cloth would be red ; but, 

 by washing and bleaching, the madder will be dis- 

 charged from every part of the cloth except where 

 the acetite ofalumine had been applied ; and, con- 

 sequently, the pattern alone will appear red. In 

 the same manner the patterns may be applied of 

 any other colour by varying the dye, as quercitron 

 bark or weld for yellow, &c. 



Two mordants are particularly employed in ca- 

 lico-printing, acetite of alumine, and iron dissolved 

 in some vegetable acid. 



The acetite of alumine is made by a double de- 

 composition of alum and sugar of lead. When iron 

 is used as a mordant, it is dissolved in vinegar, 

 soured beer, or pyroligneous acid ; and it is, there- 

 fore, an acetite of iron mixed with a portion of tar- 

 trite, gallate, and, perhaps, other salts of the metal. 



When the colour of the required pattern varies 

 in different places, this effect is produced on the 

 cloth, by impregnating the several parts with vari- 

 ous mordants. Thus, if one part is printed with 

 acetite of alumine, and another with acetite of iron, 



o 3 



