With a pen, you can paint simple patterns in pretty colours! If you happen to make a mistake, just wash and start over. The paint will not be permanent until the mug has been hardened in the oven. Remember to make sure the surface is clean and free from grease before you start painting! Thoroughly scrub the porcelain mug before painting. The area where the silicone holder was (on this particular mug) may have flecks of grease. When you're done painting, let dry for 4 hours and then harden in the oven at 160°C for 90 minutes. Dishwasher safe.