The Talking Machine Forum — For All Antique Phonographs & Recordings

Hey guys, I know this has been covered at least once in a previous page, but I don't know where to start looking for it, so here comes the subject again...Please advise me on how to flatten a warped disc record. It's a Columbia, and it has somehow become warped into a shallow bowl shape. I just bought it this weekend, and the songs sounded like they might be interesting, so I figured I'd give it a try, but it's unplayable at the moment. Any advice is welcome.

The way I have done it is to use two sheets of glass. Put the disk between the two (making sure there is no grit or dirt on the glass and leave out in the sun for a little while. You then need to take you glass sandwich out of the sun and allow to cool with the disk still between. Once cooled remove the disk and it should be flat.

You might want to experiment with a rough disk first. I used to do it this way in the UK but the sun might be stronger where you are so the time in the sun might need to be quite short. If its winter where you are then i've never tried an oven and that might be worth experimenting with although as to what temperature and for how long it would need to be baked for I have no idea. Also would glass stand up to that kind of heat?

S-B-H

Years ago in "Stereo Review" magazine there was an article on flattening warped vinyl LPs (this was even before Zappa and Weird Al!). Essentially you use two sheets of ¼"-thick plate glass about 13" square, make a sandwich with the (very clean, dust-free) record between the two (very clean, dust-free) glass sheets, and place it on the middle rack in the (cool) oven. Close oven door, turn oven on to lowest heat (e.g., "warm") for about two minutes, then turn oven off. Leave record sandwich in closed oven until it cools completely, say another hour. Repeat as necessary (a *slightly * higher heat setting is OK, but be extremely cautious, and never more than two minutes of heat "on" time; the point is to use just enough, but no more, heat than is absolutely necessary to get the job done!).

All of the above is for vinyl, not shellac, and assumes an electric oven. I agree with previous poster that you try it first with a "waste" shellac record. I know from experience that the method is effective with vinyl. However, I disagree about using sunlight as a heat source: after all, one has no control over the sun's heat intensity, especially with materials not designed to withstand or resist it. Better IMO to use a controlled heat source like the oven.

I agree with Henry, a controlled heat source would be much safer just for the fact that you do have a degree of control. Sunlight has worked for me but I have played around with doing it this way for a while - and never attempted it on anything other than records I could affford to lose. Just don't put it in the oven and forget it!

Thanks fellas! I'll do my best to not overcook it. It'll no doubt be the weekend before I have time to try, so I'll let you know how it turns out.

A hot Houston summer day and two pieces of picture frame glass worked well for me.

Steve S

I use sheets of glass and sunshine too. Once the disc is flat (this usually only takes less than 5 minutes on a fine day), I pick up the sheets with disc in place and move it inside to cool.
If you have access to a sand blaster, it's a good idea to apply a sheet of thick vinyl adhesive sheeting to one side of each piece of glass, cut a circle a little larger than a label from the vinyl, and hit it with the sand blaster to etch the surface of the glass down a bit, then remove the rest of the vinyl adhesive sheeting. (that's how they etch lettering in modern granite gravestones, most modern glass table tops etc)
Some discs have a raised label that prevents them from being flattened properly between two smooth surfaces, so you can use the etched sides for these, or flip the glass over for use on discs where the label is level with the disc surface.

Just beware of one thing- if there is any kind of crack in the record it will open up during the process.

Henry wrote: However, I disagree about using sunlight as a heat source: after all, one has no control over the sun's heat intensity.

Exposure time is your control, although you cant really set a time. You need to keep an eye on what's happening. You cant just walk away and come back in half an hour, and not expect to find a blob of molten shellac between the glass.
On a stinking hot day here the temp might be 37C, but on average it may be around 29C or so. I doubt my oven would even operate at a temperate below 50C.
But again. I guess exposure time is key.

Some discs (particularly Pathé's American sapphire ball discs) will become pliable in hot water. I found that out while washing them.