How best to eliminate LP warps

The vinyl disc is manufactured using a compression molding process. Theoretically it is a process that will induce the least amount of "molded in" stresses in a plastic part like a record disc. There are a variety of reasons why a vinyl disc made like this will warp. From the process itself, from discs not stored properly, etc. To remove the warp you need to apply a type of annealing process where you want move, or reposition, polymer chains. This can be done in an oven. You will need to set the temperature control to the desired temperature and apply a force. After time the disc should be flat. 

The glass transition temp of PVC is 83C so this is the target temp. You will need to be at or just above this temp to get the polymer chains to move. If you place the vinyl between two aluminum plates and place a weight of 1kg on top this should work.  Place a thermocouple in the oven and determine what setting is necessary to achieve 83C. It will take time to come up to temperature and then there will be a necessary dwell time to make the disc flat. The time can be determined through a little experimentation. And it will also depend on thickness of the vinyl disc. I did this before and it worked well.

@drbond thanks for the info on Mockingbird.  I saw an Orb listed here on Audigon recently, but it was almost the price of a new one, so I passed.  It did get snatched up pretty quickly.

Agree with those that mentioned using an outer ring.  If your table will accommodate one, that's a great way to go.  I had one with my VPI Classic 2 and it worked great.  

I don't think it would be a good idea to put one on my Sota Sapphire with it's suspended chassis, which is why being able to flatten my records is appealing.  I have the Sota clamp which works well, but doesn't do much for warps where the outer edge is bent upwards.

I’ll add my voice to those who recommend an outer ring. When I got one I sold my vinylflat right away.

It is far easier to use than any reflex clamp, and does the job better.

Moreover, by adding weight to the edge of your platter it will add flywheel effect and increase SQ for that reason alone. I use one with all records, warped or not.

If a research is done into using a Peripheral Ring, it soon becomes apparent that additional to the intended benefits of the increased inertia, the impact of the weight on the LP, and the reduction of the warped form around the rim, has shown, if the reports are accurate that new levels of quietness are achievable during the playback when the Peripheral Ring is present. 

Not all TT's can utilise a common design of a Peripheral Ring, so it is always best to check if the TT is compatible with the design being selected. One such design change could be the need for a shallower depth weight or a chamfered edge to a weight.

@dekay , nice thinking. The trick is there can not be any temperature differential across the record or you will make warps. Will a heating blanket and glass panes work? Sounds like a nice experiment to me!