DO NOT put heavy plate glass on the top of your prospective melted shellac
sandwich(yum).
Experience says, "One takes the risk of having the shellac filling cracking
before it softens and flattens."

Best to let the uncovered, warped disc soften before putting on the top
glass.

I don't know why it wouldn't work with a Columbia laminate. Though these may
not deform very easily, anyway.

I can't imagine what would warp an Edison record except maybe dampness and
uneven pressure in storage.  A wet core warp on an Edison probably is fixed
by finding a better copy.

LeRoy

On Sat, Oct 3, 2009 at 1:40 PM, Malcolm Rockwell <[log in to unmask]> wrote:

> Yes. Most common method is to put the record in between 2 sheets of flat
> glass, put the "sandwich" in direct sunlight until the shellac softens
> enough to unwarp the disc, remove sandwich from sunlight and let cool 2 or 3
> hours. Voila, a flat disc.
> There are exceptions to this method. It doesn't work on Columbia laminates
> or "acetate" (lacquer) discs, either.
> Ovens have been used, as opposed to sunlight, but not your home oven. And
> not a microwave.
> The softening temp usually cited is 125 degrees Fahrenheit and most ovens
> will not go that low and have any temperature control or reliability.
> I'm sure others on list will chime in about all this.
> Malcolm
>
> ******* Shai Drori wrote:
>
>> Will heating shellac records flatten them?
>>
>>