[ATM] Ceramic mirrors, fusing Pyrex to the ceramic

[vorblesnak@peak.org]

Over a few hours a second crack began to form in the glass.  No cracking
was seen in the glaze or in the ceramic.  Everything was cool to the touch
so Craig layed the tile in a saucer of water.  Within an hour there were
several cracks formed, and these have continued to expand.  It is as
though the clay absorbed the water and expanded, cracking the Pyrex.

A second run was done with a new piece of tile at a higher temp.  He took
it to 2250, (Cone 6??),  and then let it cool out.  The Pyrex was clear
and had lost all details of the shards that formed it.  It was well
adheared to the tile where a glaze wash had underlain  it.  There is a
crazing visible under the glass and we both wondered what that might be.

The program was up at 300 / hr to 2250,  let it cool down to room temp. 
No soak anywhere just up and down.

I suggested glazing the entire piece to seal the clay and prevent
expansion that caused the cracking seen in the first run.

David Davis
Toledo, OR

The new pics 2nd Test A and B are at the same place as the old ones ..

http://www.atmlist.net/contrib/vorblesnak-at-peak-dot-org/Fusing/

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