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Old 02-24-2020, 06:59 AM
Drew Hine Drew Hine is offline
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Bomma cullet-annealing

We are thinking about switching to Bomma cullet from SP Batch for speed reasons. We simply don't have time to charge batch anymore. On the spec sheet it says to cool down at this rate for pieces under 10mm:
Start at 977 (we typically run at 920 for SP)
90 mins to 770
90 mins to 392

This seemed fast for us, but has anyone had success at this rate? We are trying to weigh out all factors to come up with a solution and the increase temperature will raise the electric bill but the faster cycle will balance it out? Any thoughts are appreciated
Drew
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Old 02-24-2020, 07:04 AM
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Pete VanderLaan Pete VanderLaan is offline
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It's entirely relative to the thickness of your work. I've seen thin blown ware on a belt anneal in under an hour. I would not run glass down as quickly without at least a good soak. It does seem fast. Polarize your work.

Given the length of time people are spending with fining Bomma out, I am suspicious that the time taken to filling the furnace is vastly over rated. If you want clean glass, SP is currently the best bet. If it doesn't matter to you, any cullet will do.
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Old 02-24-2020, 09:08 AM
Shawn Everette Shawn Everette is offline
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I do a 12 hour program; 3@950, 3 to 700, 6 to 300. No issues even with 3-4" paperweights.
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Old 02-24-2020, 04:03 PM
Art Freas Art Freas is offline
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Looking for annealing comparisons for folks that have gone from Cristalica to Bomma. What was your top temp for each. Looking for the rough starting temp comparison in the same annealer.
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Old 02-24-2020, 05:19 PM
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935F would cover you just fine.
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Old 02-25-2020, 08:30 AM
Shawn Everette Shawn Everette is offline
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I was 950 on both.
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Old 02-25-2020, 08:47 AM
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Pete VanderLaan Pete VanderLaan is offline
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I actually run at 955F but I think 935F would cover you. If the ware is really thin, it could deform at 935 if left too long. Almost no one works open stemware anymore so we don't often see that.
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