HOW VARIETY OF COLOR IS SECURED 247 



evidence of high perfection in the art of dyeing and weav- 

 ing. 



Housewives who wish to do successful home dyeing should 

 therefore not purchase dyes indiscriminately, but should select 

 the kind best suited to the material, because the coloring 

 principle which will remake a silk waist may utterly ruin a 

 woolen skirt or a linen suit. Powders designed for special 

 purposes may be purchased from druggists. 



228. Indirect Dyeing. We have seen that it is practically 

 impossible to color cotton and linen in a simple manner with 

 any degree of permanency, because of the lack of chemical 

 action between vegetable fibers and coloring matter. But 

 the varied uses to which dyed articles are put make fastness 

 of color absolutely necessary. A shirt, for example, must not 

 be discolored by perspiration, nor a waist faded by washing, 

 nor a carpet dulled by sweeping with a dampened broom. 

 In order to insure permanency of dyes, an indirect method was 

 originated which consisted of adding to the fibers a chemical 

 capable of acting upon the dye and forming with it a colored 

 compound insoluble in water, and hence '"safe." For ex- 

 ample, cotton material dyed directly in logwood solution has 

 almost no value, but if it is soaked in a solution of oxalic acid 

 and alum until it becomes saturated with the chemicals, and 

 is then transferred to a logwood bath, the color acquired is 

 fast and beautiful. 



This method of indirect dyeing is known as the mordanting 

 process ; it consists of saturating the fabric to be dyed with 

 chemicals which will unite with -the coloring matter to form 

 compounds unaffected by water. The chemicals are called 

 mordants. 



229. How Variety of Color is Secured. The color which is 

 fixed on the fabric as a result of chemical action between mor- 

 dant and dye is frequently very different from that of the dye 



