Semi-opaque water-based marker with fixed felt tip for glass and porcelain. After curing in the oven, the product is dishwasher safe in mild cycles. If you need glass and porcelain markers, we can definitely recommend these, they are good for many different creative projects and can be easily used by children. If you wish to decorate your own piece of glass or porcelain, the surface must be clean and free of grease and the finished piece must be allowed to dry for four hours. Then put it in a cold oven, set the temperature to 160 degrees and let it harden for 90 minutes.