Sealing painted glass is a simple project that will protect and help the paint to resist scratching and flaking. The seal adds a layer of protection over the paint, acting as a buffer from outside influences, such as heat, bumps and oil. One or two coats of varnish over painted glass will greatly increase the lifespan of the paint. The varnish also protects the paint colours from fading or changing in sunlight over time.
Inspect the glass to determine the kind of paint used to paint on it. Water based paint, oil based paint and enamel paint are all used to paint glass. Oil paints should repel water, enamel glaze should have a hard and smooth texture and water based paint should allow water to sit on the surface.
Determine the best sealer to use for the material. For water-based paints, such as acrylic and latex, use a water-based varnish. For oil-based paints, use a spray lacquer. For enamel paints, you can also use a water-based varnish.
Wipe the painted area of the glass with a damp cloth to remove dirt, dust and oil. Do not use soaps or other cleaners on the glass, as it could cause the paint to lift away from the glass surface. Allow the glass to dry for two hours.
Dip the paintbrush into the varnish or lacquer. Wipe off excess varnish on the sides of the container. Brush the varnish over the painted design on the glass. Apply the varnish about two inches beyond the edges of the paint on the glass for additional protection. Allow the varnish to dry for two hours, and apply a second coating. Allow the glass to dry for 24 hours before trying to wash it or use it again.
Apply spray lacquer with a similar procedure. Hold the spray about eight inches from the surface and apply an even layer to two inches beyond all painted edges. Allow the spray to dry for two hours, and apply a second coat. Allow the spray to dry 24 hours before using or washing the glass.
When you wash the glass, always place it on the top rack of the dishwasher for safety, or wash it by hand.