Test, to discover whether the lacquer one uses to paint is good &c. If the lacquer is made of cochineal, it never changes. And if it is made of Brazil wood, &c., it will becomes an orange colour over time. To discover this, take a small grain of lacquer, and rub it with your nail on a piece of white paper, and put a drop of lemon juice on it. Rub it through the lacquer with your finger. If the lacquer remains unchanged, it is good, and made of cochineal. But if it turns an orange colour, it is unstable, and made of Fernambuk, or Brazil wood, and will evaporate over time, and is no good.