Silicon Carbide vs. Aluminum Oxide Firepolish Comparison Test
Micrographs by Nikki O’Neill
Samples by Tony Smith and Steve Immerman
The purpose of this page is to demonstrate some of the functional differences between the two common sandblaster abrasives. The conclusion of this series of observations is that if you plan to blast and then refire glass, that Aluminum Oxide is a preferable abrasive. It results in a surface that is quite similar to virgin glass.
The summary is that Silicon Carbide is a more aggressive abrasive, and works well for deep blasting. But, when glass blasted with SiC is refired – it traps microscopic bubbles below the surface – resulting in a hazy appearance. The photos below show the evidence for this conclusion.
“There wasn’t much to see. Very few nicks and small fractures.”
|Bullseye clear and black (non iridized) blasted with 200 grit Silicon Carbide, and fired with the blasted sides facing one another. This micrograph is focused in between the layers. Note the huge number of trapped bubbles between the layers.|
Nikki notes: “Bubbles are trapped on all layers, and fewer are evident where only one layer was blasted.
Very few bubbles, nicks and fractures, except at the edge of the piece where there are more. The interface between the two clear layers is not discernible. This demonstrates that AlOx does not trap bubbles the way SiC does.
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