Vat Yellow 1 is a

vat dye Vat dyes are a class of dyes that are classified as such because of the method by which they are applied. Vat dyeing is a process that refers to dyeing that takes place in a bucket or vat. The original vat dye is indigo, once obtained only from pl ...

, yellow in appearance under some conditions used in cloth dyeing.

References

Vat dyes Nitrogen heterocycles {{dye-stub