Semi-opaque, water-based marker with a solid felt tip for glass and porcelain. After curing in the oven, the product is dishwasher-safe on gentle cycles. If you need glass and porcelain markers, we highly recommend these; they're great for a variety of creative projects and are easy for children to use. If you want to decorate your own piece of glass or porcelain, the surface must be clean and free of grease, and the finished piece must dry for four hours. Then place it in a cold oven, set the temperature to 160 degrees Celsius, and let it harden for 90 minutes.