The wool is first dyed in the blue vat; then washed and dried; then after mordanting, dyed in the yellow bath. This method is not arbitrary as some dyers consider a better green is got by dyeing it yellow before the blue. But the first method produces the fastest and brightest greens as the aluming after the blue vat clears the wool of the loose particles of indigo and seems to fix the colour.
If a bright yellow green is wanted, then mordant with alum after the indigo bath; if olive green, then mordant with chrome.
The wool can be dyed blue for green in three different ways:—1st in the Indigo vat, 2nd with Indigo Extract with Alum mordant, 3rd with logwood with Chrome mordant. For a good bright green, dye the wool a rather light blue, then wash and dry; Mordant with alum, green it with a good yellow dye, such as weld or fustic, varying the proportion of each according to the shade of green required. Heather tips, dyer's broom, dock roots, poplar leaves, saw wort are also good yellows for dyeing green. If Indigo Extract is used for the blue, fustic is the best yellow for greening, its colour is less affected by the sulphuric acid than other yellows.
According to Bancroft, Quercitron is the yellow above all others for dyeing greens. He says:—"The most beautiful Saxon greens may be produced very cheaply and expeditiously by combining the lively yellow which results from Quercitron bark, murio sulphate of tin and alum, with the blue afforded by Indigo when dissolved in sulphuric acid, as for dyeing the Saxon Blue."
"For a full bodied green" he says "6 or 8 lbs. of powdered bark should be put into a dyeing vessel for every 100 lbs. wool, with a similar quantity of water: When it begins to boil, 6 lbs. murio-sulphate of tin should be added (with the usual precaution) and a few minutes afterwards 4 lbs. alum: these having boiled 5 or 6 minutes, cold water should be added, and then as much sulphate of Indigo as needed for the shade of green to be dyed, stirring thoroughly. The wool is then put into the liquor and stirred briskly for half an hour. It is best to keep the water just at the boiling point."
RECIPES FOR DYEING GREEN
(1) GREEN WITH QUERCITRON FOR WOOL
Dye the wool blue in the indigo vat, wash well. For 100 parts of wool put 3 of chalk and 10 or 12 of alum. Boil wool in this 1 hour. Then to same bath add 10 to 12 parts quercitron and continue boiling for 15 minutes, then add 1 part of chalk, this addition is repeated at intervals of 6 to 8 minutes till a fine green is brought out.
(2) WITH INDIGO EXTRACT AND WELD FOR WOOL
Mordant 1 lb. wool with 4 ozs. alum and 1/2 oz. cream of tartar. Dye blue with sufficiency of indigo extract, wash and dry. Prepare a dye bath with weld which has been previously chopped up and boiled. Enter wool and boil for half an hour or more.