Is it harmful to look at wood-dyed cans?

No harm. Wood dyeing is a process in which dyes combine with wood chemically or physico-chemically, so that wood has a certain solid color. It is an important means to improve the surface quality of wood, improve the visual characteristics of wood and increase the additional planting of wood. It doesn't hurt to dye the board and look at the jar. Cylinder is a container made of clay, porcelain clay, glass, etc. It is cylindrical with a big mouth and a small bottom.