The first step in the cut resist method is the formation and placing of a pattern upon the glass. A thin sheet of rubber or vinyl is attached to the item that will be sandblasted. This sheet material or "sandblast resist" will protect the area not being blasted. A pattern is transferred to the resist material using ink, pencil or carbon paper. The pattern may be drawn freehand or traced from a template. Selected portions of the pattern are then cut away. A positive etch is achieved by removing the parts of the pattern itself. A negative etch leaves the pattern intact while removing the background around it. The exposed area is then blasted with an abrasive stream to reveal the pattern.
Ultra violet sensitive film technology eliminates the need to hand cut the resist. A computer is used to generate the line art. A positive film image of the art is exposed to ultraviolet light. The resist is then washed to create open areas through which the abrasive will flow. After the resist is applied to the glass, the glass is blasted. This process is expensive and can cost up to 9 cents a square inch.
It is possible to carve three dimensional images into glass by selectively removing pieces of a pattern and blasting different areas to different depths. Adjacent pattern areas may be allowed to touch if the degree of etch is varied in each area to provide a black and white shaded look. Pattern sections are numbered and the deepest pattern sections are carved first. This carving in stages creates three dimensional sculptures in a flat piece of glass.
Once the resist has been applied to the glass, the siphon blaster is connected to the compressor and blasting begins. Blasting is done 2 to 6 inches away from the surface using a brushing or painting motion. Etching aims for a uniform frost over the entire piece while sandcarving concentrates the grit on small areas to create deeper cuts. The resist is removed from the deepest portions first and successive shallower portions are peeled and sanded until the entire piece is finished. It is important to rinse the completed item under water to remove any remaining grit.