I've noticed that my painting has started to flake off my glassware after I washed it. Why is this happening?

Are you handwashing these items? If not, are you placing them only in the top rack of the dishwasher? If so the problem may be that you did not use enough paint. You can either go over your design with more paint or with the Clear Medium. The Clear Medium will help the paint adhesion and should only be applied over your design, otherwise you may see streaks. Once you go over your design you will have to bake your glassware again or allow it to cure for 21 days. If painted glassware was not properly cured, it can cause flaking. Any water used on brushed or in paint will cause it to not adhere well.