develops a disagreeable odor, a bluish-coppery scum on top and green 

 streaks throughout, it is ready to be used. 



Wet the wool or cotton thoroughly before dipping it in the dye vat. 

 Throughout the dyeing process the vat should be kept lukewarm (95° F.) 

 and the material turned and stirred occasionally to assure even absorption 

 of dye. The material must also be lifted out and exposed to the air at 

 intervals during the dye process. Though greenish yellow in the dye liquid, 

 the material will turn blue when exposed to the air. 



Continue dipping and airing for 30 minutes, then lift the material from 

 the dyebath, squeeze out excess liquid and allow it to air for half an hour. 

 Since depth of color depends on the number of times the material is lifted 

 out and aired, repeat these steps as many times as necessary, increasing 

 each immersion time, until the desired depth of color is achieved. After the 

 last airing the material should be rinsed in lukewarm water and dried. 



Note : If the sediment in the bottom of the vat is disturbed the material 

 will be streaked and unevenly dyed. If the dyebath is stirred too much it 

 will turn blue, and thus lose its effectiveness. If this should happen, renew 

 the vat by adding more indigo, bran, madder, and sodium carbonate. 

 Allow it to stand undisturbed for one or two days and it will again be 

 ready for use. In this manner the blue-pot can be replenished and reused 

 many times. 



Method 2: Indigo Hydrosulfite Vat 



The hydrosulfite vat is the most easily regulated of the indigo vats and 

 is used extensively among indigo dyers. Both wool and cotton can be 

 dyed in the hydrosulfite vat without mordants. When top-dyeing, 

 however, the material should be mordanted with alum either before or 

 after dyeing with indigo, depending on the nature of the other dyestufF. 



The following quantities are sufficient for dyeing 1 pound of wool or 

 cotton. First make up the following two stock solutions: 



(A) Indigo Hydrosulfite Solution 



4y^ ounces powdered indigo 

 3 ounces sodium hydroxide 

 2% ounces sodium hydrosulfite 



Mix the powdered indigo with sodium hydroxide which has been dis- 

 solved in water, add enough water to make 1 gallon of solution ; then heat 

 it to 120° F. Stir well while slowly adding the sodium hydrosulfite. Allow 

 the solution to stand for 30 minutes. The liquid should be clear and yellow. 

 A drop running along a glass plate should turn blue in about 25 seconds. 

 Measure out 2 to 2}^ quarts of solution for the dye vat. Store extra solution 

 in a stoppered bottle. 



90 



