How best to eliminate LP warps

@poorguy I never learnt what the metal was that is used on the AT-666.

I know others use this mat on this forum, and it might be possible to learn which metal is used if a wider inquiry is made.

I also know through this forum, it has been used without a Vacuum and has been rated as an attractive method, I have not heard the mat used in such a way, but would try it out in the near future, as I will be visiting the owner of the one I have tried out.

Again there are AT 666 owners on here who can offer a description with almost immediacy if willing to help.

The AT 666 is not always going to be able to successfully hold a Vacuum for a full period of a side of a LP, their age is contributory to this, the length of time the Vacuum is in place is a unknown, some do not produce a Vacuum anymore.

With the above in mind, it does suggest careful selection is required, when purchasing,  if a Vacuum is the important function for the mat.

I am wondering if AT-666 uses the same metal- magnesium- as 

.

I'd say unless the record is unplayable live with minor warps.

I've tried traditional and modern methods of trying to flatten reocrds with varying degrees of success.

Last machine used was the AFI Flat.

Most of the time it works pretty well, but it has ruined several records including a numbered Blade Runner soundtrack on red vinyl and a sonically mint early pressing of Fleetwood Mac Rumours.

The Blade Runner was a strange one as I had successfully flattened many colored records but QRP must have used some non-standard vinyl formulation that made it susceptible to heat damage. After treatment a rough orange peel pattern appeared on the record and it was unplayable. Other owners of this record have also experienced ruin using a variety of de-warping methods.

Caveat emptor when using these devices.

I have figured out the material of the plate of AT-666 from 

.  It's made of aluminum.

The Vinyl Flat and Groovy Pouch has worked great for me.  I got one for my birthday in March of this year.  Every warped record that I've tried to flatten came out nearly 100% flat.  I first preheat the Vinyl Flat in the Pouch to 130-140F.  Then I put the LP in the Pouch at medium temperature and monitor the temperature to keep it 130-140F.  After 2 hours, I unplug the Pouch and let the Vinyl Flat cool while still in the Pouch for another 2 hours.  Every record, both brand new and used ones from the 70s and 80s have come out flat.