To reuse, clean with a non-abrasive sponge under cold water. POP glasses are not dishwasher safe and are not compatible with heat or hot liquids.Separate your stacked glasses by breaking them apart like you would a chocolate bar.Feel free to use the glasses straight out of the sleeves upon receiving them. Our products are made in food-grade facilities with the highest level of cleanliness. After use, place them in the recycling bin so they can be made into more cups. Or jackets. Or carpets. You get the idea.