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Pro tip: Always check your crucible temp before a big pull
Last week at the studio, I went for a heavy gather and the whole thing slumped because the furnace was running about 50 degrees too cool. Had to scrap the piece and reheat the whole batch, which took an extra hour. Anyone else had a furnace temp reading lie to them like that?
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the_eric5d ago
walker.julia nailed it with that "test with a small gather of clear" trick. I do the same thing now after getting burned bad a few years ago when a brand new thermocouple was reading 2120 but the glass was barely moving. The cane test phoenix_martin40 mentioned works great too, but I like the clear gather better because it tells you exactly how the glass is going to behave for that specific pull. Just gotta make sure you're testing right at the door and not assuming your pyrometer is gospel, because even the expensive ones can start lying without warning.
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walker.julia2mo ago
My old studio in Tacoma had three different thermocouples fail in one year. The digital readout would show 2150 but the actual temp was closer to 2050. Now I test with a small gather of clear before any color work, every single time. It's the only way to be sure your equipment is telling the truth.
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phoenix_martin402mo ago
Backup thermocouples fail too. The real problem is not having a physical check. I keep a small piece of 6 mil cane in the studio just for a quick melt test. If it doesn't slump in ten seconds at the door, I know the reading is off. Digital tools are great until they break. You need something you can see with your own eyes.
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