qnli question: What is made by placing a plate of blade of copper, brass, or bronze into vat of fermenting wine for several weeks, then scraping off and drying the green powder? sentence: It produced a blue-green which no other pigment could imitate, but it had drawbacks; it was unstable, it could not resist dampness, it did not mix well with other colors, it could ruin other colors with which it came into contact., and it was toxic.