Black Oak - sawdust of the inner bark of the Quercus velutina tree found in eastern North America. This strong yellow dye was "discovered" by Edward Bancroft who marketed it as Quercitron (by combining its Latin name for black oak with "citron" for yellow). Anxious to promote his find, he claimed the dye to be four times as strong as old fustic and up to ten times more powerful than weld. It is undoubtedly a strong dye, producing attractive, rich yellows on mordanted fibers, both protein and cellulose. It gives one of the best old gold colours on cotton and linen. It is a very lightfast dye and requires 10-20% wof for a medium depth of colour.