Uses for a sandblaster

There are several important uses for a sandblaster which makes it an indispensable tool for kilnformers.

Fixing surface problems:  One common use of a sandblaster is to remove shelf separator that has adhered to the back surface of glass during firing. (see image on right) Although there are manual methods of removing this, none is as easy and successful as a light sandblasting (15-20 psi).  When the back side of a piece is sandblasted it will have a dusty, frosted appearance. This will stay dusty and frosted looking if slumped as the next step. If a glossier bottom side to the piece is desired, either a separate trip through the kiln for firepolishing is needed, or a product can be applied after slumping, such as Armor All, Liquid Lust’er, or Watco Oil.

Repairing surface devitrification:  As any experienced kilnformer has found out, there are times that kiln fired glass develops a haze due to a crystallization of the surface glass molecules. This is called devitrification. It is less common with art glass specifically formulated for kilnforming – but it still occurs at times, especially with glass that hasn’t been scrupulously cleaned, opalescent glasses, glass in close proximity to Thinfire® paper, and glass that is fired at high temperatures for long times. Once this occurs the haze cannot be removed without some sort of process which actually removes the outer surface later of the glass. Options include manual grinding with diamond products, chemical etching – or, best of all, sandblasting. A light blasting of the entire surface of the glass, including the edges, and then subsequent fire polishing at a lower temperature than the original firing will yield a glossy surface. The photo to the below shows the appearance of devitrification on opalescent glass.

Removing surface debris: There are times that mysterious spots appear on our fired glass. These can be caused by debris falling from the roof of our kilns, small particles of glass that get in the wrong place, or metal dust from our work surface that adheres to the glass. If you’re a perfectionist, one tiny spot can ruin an entire project. Often, the only way to make a repair  is to sandblast the surface until the spots are gone, and firepolish at temperatures around 1340-1390F.

Removing iridized coatings: Glass for kilnforming can be purchased with an iridized coating, and there are times that we want to remove some of this coating for artistic or technical reasons. Light blasting is an excellent way to accomplish this. (see first image on page one of this article)

Obtaining a matte finish:  Although many people like their glass projects to be bright and shiny, there are times when a matte or semi-gloss finish is preferable. Lightly blasting the surface and refiring to slumping temperatures (1100-1175F depending on your kiln and the hold time) will give a very nice, non-glossy surface. Below is an image which shows the frosted appearance of sandblasted glass

Conclusion

There are many other ways to use a sandblaster for glass art – and I’ve just scratched the surface of the subject. Hopefully, this article has made you aware if the many uses, and has given you enough information to consider purchasing a system of your own.

Links for more information:

Tony Smith's Blasted Glass Studio