Decide whether you want the paint to appear opaque or transparent over the glass. If you want an opaque look, find Liquitex Glossies. As of late 2009 you can purchase two-ounce jars of this paint for $4 to $5. Delta PermEnamel is slightly less expensive at about $3.50 for a two-ounce jar. If you want a transparent paint, look for resin-based paints such as Pebeo’s Vitrea 160, about $6.50 per 1.5-ounce jar. You can choose from a wide selection of colors in opaque and transparent acrylic paint. You’ll also need a few soft paintbrushes.
Clean the surface of the glass thoroughly with soap and water to remove any dirt or dust, and let it dry. Experiment with your flower designs on paper before painting them directly on the glass. Try out a variety of flower shapes and patterns. If you’re less confident in your artistic skills, work from stencils or printed images of flowers.
Once you have settled on a design, begin painting directly on the glass. If you want your painted flowers to appear opaque, do not add water to the acrylic paint; water will thin the paint and make it appear more transparent. Use a small brush for detailed flowers.
Let the paint air-dry when you are finished. If you used Pebeo’s Vitrea 160 acrylic paint, then let the paint dry and then bake the glass in the oven. The heat will give the paint an iridescent, stained-glass appearance. Place the glass in the oven while it is at room temperature, and let the glass warm gradually along with the oven. Bake at 325 degrees Fahrenheit for 40 minutes, and then let it cool gradually to room temperature.