The use of "powder wafers" is a process for creating surface decorations on kiln-formed glass. Bob Leatherbarrow, a kiln-formed glass artist from Calgary, Canada, is widely credited with developing this technique.
Powder wafers are created by sifting glass powder directly onto a kiln shelf and then firing to an appropriate temperature at which point the powder is fused into a single - and fragile -- piece of glass. The exact firing schedule varies greatly depending on powders used, the desired effect and the specific kiln being used.
A wide variety of designs and effects can be achieved using different sifters, tools, stencils and more. Leatherbarrow actually uses a vacuum as a tool in some of his work.
A key advantage to powder wafers is the ability to create design elements and then place and move them on the glass before committing to a design. Once a final position is determined, powder wafers are usually fused to a piece of sheet glass.