YELLOW
WELD OLD FUSTIC TURMERIC QUERCITRON DYER'S BROOM HEATHER AND OTHER YELLOW DYES
Weld, Reseda luteola, is an annual plant growing in waste places. The whole plant is used for dyeing except the root. It is the best and fastest of the yellow natural dyes.
The plant is gathered in June and July, it is then carefully dried in the shade and tied up in bundles. When needed for dyeing it is broken into pieces or chopped finely, the roots being discarded, and a decoction is made by boiling it up in water for about 3/4 hour. It gives a bright yellow with alum and tartar as mordant. With chrome it yields an old gold shade; with tin it produces more orange coloured yellows; with copper and iron, olive shades. The quantity of weld used must be determined by the depth of colour required. Two per cent of stannous chloride added to the mordant gives brilliancy and fastness to the colour. Bright and fast orange yellows are got by mordanting with 8 per cent stannous chloride instead of alum. With 6 per cent copper sulphate and 8 per cent chalk, weld gives a good orange yellow. Wool mordanted with 4 per cent of ferrous sulphate and 10 per cent tartar and dyed in a separate bath with weld with 8 per cent chalk, takes a good olive yellow. 8 per cent of alum is often used for mordant for weld. A little chalk added to the dye bath makes the colour more intense; common salt makes the colour richer and deeper.
Weld is of greater antiquity than most, if not all, other natural yellow dyes. It is cultivated for dyeing in France, Germany and Italy. It is important as it dyes silk with a fast colour.
(1) OLD GOLD
Mordant with 2 per cent chrome and dye with 60 per cent of weld in a separate bath. 3 per cent chalk adds to intensity of colour.
(2) YELLOW
Mordant with alum, and dye with 1 lb. of weld for every pound of wool. Common salt deepens the colour. If alum is added to the dye bath, the colour becomes paler and more lively. Sulphate of iron inclines it to brown.