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Hello Glassies,

Honestly, I have graduated from most crack and bubble questions, but this one I haven't seen. I have a textured fused piece which has been fired 3 times I believe and yesterday I sandblasted it. I wanted to fire to 1150 ala Tony Smith, but I see a small 1/2" crack in the platter just off the center which I can't explain. The glass varies in thickness due to texture and build up of glass pieces but is never thicker than 3/8" or so. The little fissure is in a thick area. Could I fire higher to mend the fissure but loose my sandblast? Can I fire to 1150 and live with the crack? Is the piece doomed?

Any and all advice gratefully received.
Leslie

Leslie,

The piece is salvageable. To heal the crack you will need to go up to at least 1400°F. If there the check goes through he thicker section as indicated I suspect you did not anneal log enough. When you reheat take it up very slowly (as slow as possible) to minimize the crack from spreading, and when you anneal gauge the time based on the thickest section. I don’t think it is possible to save the sand blasting you did. I don’ think you will be able to get away with just going up to the annealing temperature. As long as the crack is there and not healed it will have a possibility of lengthening anytime it experiences a temperature change.

Tim

Thank you, Tim

Will the danger of the crack spreading be there even if the crack is only on one side of the glass? It didn't appear to go all the way through.

Leslie

Leslie,

The crack will run three dimensionally until it runs to an edge. Generally, the crack will spread out horizontally through the glass first. Eventually though, the crack could propagate vertically through the glass.

Tim