There are many ways to apply paint to glass. Most paints are not permanent in nature and fade over time. The only permanent "paints" are those made of powdered glass and are fired in a kiln, fusing the "paints" into the surface of the glass so that they become one. This is the type of painting that was done in mediaeval and renaissance times. The magnificent church windows found in cathedrals worldwide attest to the permanency of the technique.

The ancient process of coloring glass is very involved. First, the artist mixes the powders with binders such as clove oil or gum arabic. When the proper consistency is achieved, the artist draws in the outline tracing of the work and fires it on in the kiln at temperatures between 1100-1200 degrees. Thereafter, the artist brushes on washes of tone and color, one at a time, working from the darkest tone to the lightest. Each tone application requires the artist to brush away the area where the next lightest tone or color will be, prior to the firing. The washes are very transparent and the colors and tones need to be intensified with each firing in order to achieve depth. Adding to the complication is the fact that certain colors mature at different temperatures because of their metallic content. Reds and red derivatives, because of their gold content, for example, fire at only 1050 degrees and burn out at 1100 degrees. The artist has to take into consideration firing and maturation temperatures when planning color washes. Additionally, the artist must make sure that no fingerprints get onto the glass since the oils from the fingers will also fire into the glass, ruining the piece. Each firing must have controlled temperature rise and controlled temperature reduction so that the glass doesn't become brittle or break.

The wolf painting (pictured in the gallery) is the result of 18 firings. The tiger took 22 firings. These paintings are an example of an ancient technique applied to modern subject matter.