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Old 11-15-2017, 12:00 PM
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Pete VanderLaan Pete VanderLaan is offline
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Since you have polarized filters, make a simple cup with some of the white chips. Look at that. Then make a cup with the white inside and clear outside, Cut it on a saw. That will tell you a bunch.
Normally, checking through the base where the punty mark is and that's often a sign of being under-annealed. You do say however that you are finishing the piece heating that very spot and you may in fact be introducing strain doing it.
As to the white being a mismatch, it's entirely possible since different batches are ..well, different. None of those whites are really close to a 96 but they have so much lead in them that they are rather tolerant.

If you make the witness weight in clear and do what you do to the base, does it show retardation of light at that point?
Also, you don't say the actual size nor do you say what the schedule on annealing is. That's rather important information.
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