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Flattening warped lp's with Seal dry mount press

I've been meaning for some time to try a test flattening warped lp's with my Seal dry mount press. A recent purchase of two warped White Stripes lp's & the recent tread that Albert Porter & others have had about the topic prompted me to start an experiment. For the first test, I placed a warped 70's Columbia pressing in the press between a 1/2" tempered glass plate and a 1/4" thick acrylic plastic plate, setting the thermostat at 165F. I did not pull the press handle to clamp, I just let the weight of the heating platten do the work as things softened. After an hour, the vinyl was quite flat and I let it cool down for the afternoon. While it looked excellent at first glance, there are problems. There is radial runout now, about 1/8" or so. Even worse, there are small hills and valleys in the vinyl surface that set my Grado Sonata wiggling and shaking. Evidently, the heating, pressing, and cooling process is creating stresses that leave things less than perfectly circular and flat. Next, I'll experiment with less heat and longer thermal heating and cooling cycles to see if stresses can be relieved to achieve better results. At this point though, I don't think I'd run out and buy a dry mount press hoping this to be an easy fix. It's going to take some experimentation to see if this will work. I'll post results as I work through the variables.
photon46
photon46 OP
1,085 posts
 
Nsgarch, yeah I know the sandwich thing uses materials that may be difficult to obtain for some. My job developing and photographing Fine Art sculpture editions gives me easy access to many materials. Plus it encourages my propensity for overly elaborate solutions! There hasn't been much sun here in Florida for the last month to try the glass sandwich, it's just rain, rain, rain.
nrchy's avatar
nrchy
2,124 posts
 
It occurs to me that the record flattening machine I saw at ces was just two glass platters, but I could be wrong.

The obvious solution to your cooling issue is CRYO! Nothing 'audiophile' works if it's not cryo'd
pdennis1f360
1 posts
 
For those of us who don't have the bucks for a seal press, anyone out there think two glass platens in the kithcen oven set to 140 degrees could work?
Peter
nsgarch's avatar
nsgarch
2,524 posts
 
pdennis -- If you want to try the glass/oven method, use 3/8" thick glass. 1/4" may not provide enough even weight, and 1/2" may not heat and cool evenly. You should also observe the following:

1.) Make sure your oven really goes down to 140 degrees. Many don't. Test it with an accurate thermometer first.

2.) Believe it or not, gas ovens are better (more even heat inside the oven chamber.) If you only have an electric oven, place a large broiler or baking pan on the lowest rack position right over the heating element to avoid direct heating of the lower piece of glass.

3.) Wait until the oven has remained at the desired temperature for a half hour or so to insure even heating. And then place the record/glass sandwich on the middle rack.

4.) For cool-down, don't move anything. Just turn off the oven and crack the door open until everything reaches room temp.
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