How to flatten Vinyl Albums

Do a search of prior thread "warped lp's," it will give you a bunch of info.

There is a treatise on a company making units to flatten LP's in the October Stereophile. This may be the safest bet to flatten valuable LP's.

...and expensive.

glass in the oven will do fine. 10 minutes may be too short though. Be sure to leave it in the oven for the 24 hours with the oven off unless you like your licorice pizza crispy.

Rega glass platters work great because they're the optimal size and the thickness gives you the optimal weight, without the books as well as distributing and holding the heat optimally.

I did it the following way: I placed the record between to pieces of granite, set in the center of my backyard with my tool box on top. I did it in mid July. Left it out for an hour or so, then turned the water hose and cooled it down. It's the only good thing about summer in the Great Southwest Desert. Tarsando do you leave the cover on or off ;

Vegasears... I leave the cover off. Otherwise, the cardboard gets meshed in with the vinyl and it's harder to track. Plus, really, since the issue is flatness, the direct contact of the steel-belted radials with the bare lp stands the best chance of achieving maximal flatness. Hope this helps. (And because you mention it, I too live in that selfsame desert and do my best flattening in the summer before monsoons hit).