The look of Quercitron dye. In 1785 Dr Edward Bancroft (American) was awarded a British patent for the very stable Quercitron yellow dye from the North American Oak tree, "Quercus tinctoria". Previous yellow dyes, including Weld tended to be fugitive. The House of Lords would not grant a 7 year extension of the patent in 1799.
Quercitron gave a range of yellows in the 'drab' style. All were very fashionable until the 1820s.