mordanted wool in the dyebath, thoroughly rinse it and squeeze out excess 

 moisture. Immerse the wool; heat to boiling; boil for 30 minutes. Without 

 rinsing, transfer the material to a boiling bath of potassium dichromate 

 and acetic acid, stir and continue to boil for 10 minutes, rinse and dry. 



HoLLYGRAPE RooT {MahoTiia sp.) 



The coloring matter contained in hoUygrape root is berberine, the same 

 as that present in the bark and root of barberry. It is one of the few natural 

 basic dyestuffs. HoUygrape or Oregon grape grows in the Northwestern 

 States. Its colors are not fast on cotton. 



Buff Wool : alum mordant 

 Colorfastness : fair 

 1 pound wool 

 1 peck chopped hoUygrape root 



Use alum mordant (see pages 67 to 68). Cover the chopped root with 

 water and allow it to soak overnight. The following morning, boil it in the 

 soaking liquid for 2 hours. Strain out the particles of dye material and add 

 water to make a dyebath of 4 to 4}^ gallons. Before immersing mordanted 

 wool in the dyebath, thoroughly rinse it and squeeze out excess moisture. 

 Immerse the wool; heat to boiling; boil for 30 minutes, rinse and dry. 



Light Tan Wool: alum mordant 

 Colorfastness: fair 

 1 pound wool 



1 peck chopped hoUygrape root 

 y^ ounce potassium dichromate 

 )(, ounce acetic acid, or 6 to 7 tablespoons vinegar 



Use alum mordant (see pages 67 to 68) and follow directions for dyeing 

 "Buff Wool" (above). Without rinsing, transfer the material into a boiling 

 bath of potassium dichromate and acetic acid. Stir and boil 10 minutes 

 longer, rinse and dry. 



Indigo (Indigofera sp.) 



Indigo was America's most important dyestuff during the 18th and 

 19th centuries. Although dyeing with indigo requires both time and 

 patience, the blue shades it produces are very fast to light and washing 

 on both wool and cotton. Indigo does not require a mordant. It belongs 

 to the class of dyestuffs known as vat dyes — so-called because they are 

 applied in a special dyebath called a vat. 



The following is a simplified explanation of what takes place in the 

 indigo dye vat: 



88 



