Drawing on porcelain doesn't have to be hard. If you make a mistake, just wash it off and start over. METHOD: Wash the mug thoroughly and then avoid touching the surface to be decorated. Draw and let dry for 4 hours. Then harden in the oven at 160 degrees for 90 minutes. After hardening, the painted object withstands the dishwasher up to 60 degrees. BLACK & RED MUGS: Make the black pattern and harden in the oven according to the directions above. Then paint the red pattern. By hardening in between applications, there is no risk of the red pen dissolving the black ink; you will be able to paint over the black pattern. Let dry and harden once more according to the instructions above.