What Paint To Use On Mugs Painting Portraits On Ceramic Mugs?

Painting portraits on ceramic mugs? - what paint to use on mugs

I had an idea for Christmas gifts to make drawings in color on the white cups and / or plaques. Not sure how to make this right. Is there a special kind of cup that I buy, or go to a blank white cup in the store? Has to be unglazed, or what? What kind of ink or paint is best to use? How can I ensure that I do not wash? Can anyone help?