SirSpeedy, may I suggest getting an IR thermometer to measure what heat is required? I have purchased one myself solely for a DIY record flattener experiment as well. I just need to get 2 glass sheets cut for this project then I will start. I like your idea of using cork adhesive on the sides that will touch the record.
I will report back on my results as well. I hope to have exact temperatures for everyone.
Kevin at KAB Electro Acoustics mentioned to me a way to go about flattening records:
1. Have 2 sheets of glass for the project.
2. Preheat your oven, bring it up to a specific temperature (the trick is to find the optimal temperature).
3. Slide in your glass-record-glass sandwich flat into your oven and at the same time turn your oven off.
4. Let your oven cool naturally along with your vinyl sandwich.
The trick is to find the precise temperature so that your record doesn't melt entirely, but just soften up so that the pressure from the glass will flatten it.
The idea is to start at a moderate temperature like 90 degrees or so. And of course, try it out on records you don't care about or buy some cheap junk records to test with until the exact temperature is discovered.
I too would like a record flattener, I think it is a required accessory to have in these modern times. New vinyl is pretty bad, and there is the occasional warped used record. The nice thing about buying warped records is they usually do not have a lot of usage/wear because they aren't played as often.
