It depends on how thin it is. There is no 100%, the thinner the more is transmitted (weighted by the curve shown in the linked article). A solid block of steel would be transparent if you illuminated it with enough light.
It depends on how thin it is. There is no 100%, the thinner the more is transmitted (weighted by the curve shown in the linked article). A solid block of steel would be transparent if you illuminated it with enough light.