How best to eliminate LP warps

You can place a thin felt washer on the spindle prior to placing the record on the platter. Then, using a record clamp, such as the one from the Record Dr., gently clamp down the record until the warp is diminished. It will not totally get rid of the warp, but the severity of the warp will be greatly lessened and your LP will play with no discernable negative effects from what warp may remain. This is generally how the more expensive Mitchell record clamp works.

Why not on direct sunlight between the 2 glasses?

The device you are looking is called Vinyl Flat Record Flattener from vinylflat.com.

audioguy, I disagree that the method you mention works well, certainly not for both sides of the same LP, because warps in one direction that may be ameliorated would not be affected as much or at all, when you flip the LP. I do have a SOTA reflex clamp, so I could give it a try for at least some of my warped LPs.

I just found the Orb too.  Much less expensive than the Furutech, but still not exactly cheap.  Anyway, that seems to be the best device currently available.

@lewm

I’ve looked into this, as I recently acquired alot of vinyl. Unfortunately, I’ve found that some of the Mint LP’s that I’ve bought tend to be warped, as they’ve never been opened in 60 years, but just lying around diagonally on someone’s shelf.
There are two real options at reasonable prices: I think the best would be the Orb DF-01A for about $1,200, but they’re only for sale in Japan, and only at 100V. So, I purchased a Vinyl Flat and Groovy Pouch combination for about $300. It took me quite a while to determine the best time and temperature settings for the Groovy Pouch (which is just an electric blanket with velcro that you wrap around the Vinyl Flat discs). They recommend the low settings for up to 9 hours, but I’ve found that the only thing that’s really worked for my warped LP’s is the high heat setting for 4 hours. . . From what I’ve heard, there’s been no discernable damage to the LP..

As @petg60 and @drbond just said, The Vinyl Flat Record Flattener, $159.95 direct from Vinyl Flat. Accessory heating bag The Groovy Pouch $89.95. Both @slaw and I (and Mike Fremer, etc.) have found it to work very well.

Mild/"slow" warps can sometimes be eliminated by the use of a good reflex clamp, standard on the old VPI’s (1/4-20 threading). It’s best if the top of the spindle is threaded, and of course the clamp itself. BDR made a couple of great ones, one a 1-pc. the other a 2-pc. I believe there is a 2-pc. on USAM right now, priced at $150.