Why Won't This Freaking Glass Paint Stick

Painting glass can be a real exercise in frustration. By its nature, glass resists adhesives, which are exactly what glass paints are. Runs, lumps and flaking can ruin your project and your day, but there are some things you can do to ensure that you get good results.

• Wash the glass thoroughly. A trip through the dishwasher simply isn't enough. Most dishwashers leave a thin film of detergent or tiny spots that will interfere with your glass paint. Wash the glass by hand, rinse it completely, then rinse it again. Let it air dry overnight before you begin working with it.
• Break out the alcohol. Glass should be swabbed with isopropyl alcohol and allowed to dry before you try to paint or glaze it. A light coating of alcohol applied with a cotton swab usually does the trick, and the alcohol will dry off almost immediately. This step gets rids of any oils and residue that washing leaves behind.
• Wear gloves. Every time you handle your project, oil transfers from your skin to the surface of the glass, preventing your paint from bonding. Latex gloves give you a good grip and keep oil away. If you're allergic to latex, wear thick cotton gloves, and be sure to wash them after you've been using them for a few days.
• Be cautious when thinning. Glass paints shouldn't need to be thinned. If they do need thinning, use the tiniest amount of thinner possible. Too much thinner throws off the chemical balance in the paint, which will cause flaking as it dries.
• Don't mix paints. With so many colors to choose from, you shouldn't need to mix paints to create custom colors. If you do have the urge to mix, follow this simple rule: Only mix paints from the same line. You can't mix paints from different manufacturers or air-drying and thermohardening paints. Mixing different paints messes up the chemistry, causing lumps, poor adhesion and flaking.
• Check your oven temperature. If you're using thermohardening paints, make sure your oven's temperature is accurate. An oven thermometer will let you know if it's hot enough for the paint to set. Older ovens tend to have inaccurate gauges, making a thermometer a must.
• Allow adequate drying time. Glass conditioners used in some paint lines and the paints themselves need the right amount of drying time. Check the label for the manufacturer's recommendations, and don't handle the pieces while they're drying.
• Wash with care. Air-drying glass paint isn't meant for pieces that will be handled and washed. Thermohardening paint can stand up to cleaning, but your pieces should always be washed by hand with gentle dish soap and a paper towel. Using a scrubbing brush or sponge, or putting hand-painted pieces in the dishwaser will cause the paint to flake.