Combine 1 tbsp of acetone nail polish remover with 1 tbsp acrylic craft paint in a plastic cup. Use a wood or plastic stirrer to mix well. You can also pour the acetone and paint directly into the glassware, assuming your stirrer can reach the bottom of your vessel.
Pour mixture into the glassware and swirl it around to coat the inside of the glass. (Make sure you protect your work space.) Tilt and roll the glass around with your hands until you have the entire inside coated with paint.
Let your painted glassware dry upside down on a paper towel for about 20 minutes. This will allow the excess paint to drain out. Then place upright and allow to dry overnight or for at least 24 hours to be sure the paint has completely dried.
Place your painted glassware on a parchment paper or aluminum foil-lined cookie sheet and place in a cold oven. To avoid breakage, do not place glass in a preheated or hot oven! Set oven temp to 350⁰F. Once the temperature reaches 350, allow the glassware to bake for 30 minutes.
After 30 minutes, turn the oven off and let the glass cool completely before removing from the oven.
How To Create Waterproof Painted Glass - Ideas for the Home by Kenarry®