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I would be very impressed if he actually will vouch for every tub maker that they do not under any circumstances exceed the elastic or plastic limits of the product as they form it? Will he vouch that the temperature of the ovens is not only correct, but perfectly even, and if it has designed-in variations in heating that those variations are perfect for the mold in use?
There are a boatload of possible variables and even changes between the sheet as it goes out the door of the plastic plant and when I see it as a repairman, in use. I think we can both be right. 8-)