Glass & Porcelain Opaque is an opaque paint for use on glass, porcelain and ceramics, available in 20 colours and sets. As the paint is not transparent, it is used mainly on porcelain and ceramics. But also on glass the opaque areas can create some extraordinary effects. Apply the paint using a sponge or flat brush, or use sticks to create the dots. Let the paint dry for 45 minutes and then fix the work in a kitchen oven. Place the painted object in the cold oven, set the oven to 160 C and bake the work for 45 minutes once the oven is at the right temperature.