quercitron

It is a constituent of the dye quercitron.

'Flavin' is the commercial name for quercitron.

The inner bark of the black oak contains a yellow pigment called quercitron, which was sold commercially in Europe until the 1940s.

The ruddy-orange decoction of quercitron contains quercitannic acid, whence its use in tanning, and an active dyeing principle, quercitrin, C21H20O12 .

'Quercitron' is a yellow dye obtained from the bark of the Eastern Black Oak ('Quercus velutina'), a fine forest tree indigenous in North America.

It was the most common yellow dye in Europe from the Middle Ages until the 18th century, when it was replaced first by the bark of the quercitron tree from North America, then by synthetic dyes.

The dyestuff is prepared by grinding the bark in mills after it has been freed from its black epidermal layer, and sifting the product to separate the fibrous matter, the fine yellow powder which remains forming the quercitron of commerce.

They are common in redwoods barks like Sequoia sempervirens or in oak barks where the chief constituent, quercitannic acid, a molecule also present in quercitron, is an unstable substance, having a tendency to give off water to form anhydrides (phlobaphenes), one of which is called oak-red (CHO).

Two brilliant yellow dyes of commercial importance in Europe from the 18th century are derived from trees of the Americas: quercitron from the inner bark of oaks native to North America and fustic from the dyer's mulberry tree (Maclura tinctoria) of the West Indies and Mexico.