and with alum, a light yellow. Cochineal mordanted with alum gives a 

 red and with chrome, a purple. 



Both wool and silk have the property of holding chemicals in their fibers. 

 For example, when wool is boiled in a solution of potassium dichromate 

 (chrome mordant) a certain amount of chromium oxide is held in the fiber, 

 and the dyestufF then combines with this mordanted wool to form a perma- 

 nent color. 



Cotton and the other vegetable fibers do not absorb mordants as readily 

 as wool. Vegetable fibers, however, combine well with tannic acid, which 

 is used either as a mordant or as an agent for fixing mordants in the fiber. 



Mordanting Wool 

 Alum Mordant 



For 1 pound of dry wool, use 



4 ounces potash alum (aluminum potassium sulfate) 

 1 ounce cream of tartar 



Dissolve the alum and cream of tartar in 4 to 4}^ gallons of cold soft 

 water. Immerse the wool after first wetting it thoroughly and squeezing 

 out excess moisture. Gradually heat the mordant bath to boiling; boil it 

 gently for 1 hour. While the wool is in the solution, it should be turned and 

 stirred to insure complete penetration of the mordant. As liquid boils away, 

 add more water to maintain the original level of the bath. Allow the wool 

 to stand overnight in the mordant. The following morning squeeze out 

 excess moisture, roll the wool in a dry towel, and store it in a cool place. 

 Rinse the mordanted material well just before immersing it in the dyebath. 



Chrome Mordant 

 For 1 pound of dry wool, use 



Yi ounce potassium dichromate 



Dissolve the potassium dichromate in 4 to 4}^ gallons of cold soft water 

 and follow directions for mordanting wool with alum. 



Mordanting Cotton 



Alum Mordant 



For 1 pound of dry cotton, use 



4 ounces potash alum (aluminum potassium sulfate) 

 1 ounce washing soda (sodium carbonate) 



Dissolve the alum and washing soda in 4 to 4}2 gallons of cold water. 

 Immerse the cotton, after first wetting it thoroughly in clear water and 

 squeezing out excess moisture. Stir while gradually heating to boiling, then 

 boil for 1 hour. Allow the yarn to remain in the bath overnight. The follow- 



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