Frank said:Edge warps are the hardest to fix warps. Your average heat warp happens when the record became soft enough for the vinyl to deform. These deformations are caused by tensions that were created while pressing a thick glob of soft, hot vinyl into a thin, flat record. These tensions remain stored inside the record and cause it to warp once the material becomes soft enough again for these powers to shift the shape of the vinyl. Take a worthless record and play it on a turntable in direct mid day sun and you will notice the record warping up and going flat again as soon as you shade it with a record cover or whatever else. If heat exposure is prolonged the warp will remain after the record cooled off.
These warps can in many cases be fixed with a de-warping machine. Edge warps however are different. They are caused by only partial heat exposure and fixing them is super tricky because in order to try doing this you will have to heat up the entire body of the record. I only had to try fix an edge warp a couple of times. First time was in Berlin during the winter so the glass plates and sun method wasn't an option. I resorted to the oven - which caused fatal heat damage on the grooves, resulting in a constant low frequency noise so I had to ditch the record. Most consumer ovens don't heat up slow enough, in fact a short pre-heating phase is what the engineers and manufacturers aim for so the oven will begin heating very rapidly and then slow down once the desired temperature is reached but until then the actual temperature will peak at much higher points than the temperature you selected. So stay the hell away from that oven (no nazi jokes please)!
Much later I successfully managed to improve another 45 edge warp with the glass plate & sun method to a degree where the record would play noise free and without a skip. But always keep in mind that you won't be able to ever get an edge warp perfectly flat so once you can play it don't go for an additional and purely cosmetic fix just because you think you can, you might be tragically mistaken and there will be no way back...
If you're close to the equator I'd avoid mid day sun from 10am-2pm. I'd wait for a clear and cloud free day to ensure equal conditions for subsequent procedures. Don't aim for an immediate fix but go for the sensitive approach with repeat treatments in order to avoid overheating. Start with 30 minutes of exposure before 10am or after 2pm. Use a perfectly flat and heavy table and make sure to place it where there will be no possible interference of any shadow producing structure nearby. Use the heaviest, thickest glass you can find and have it cut in even squares so weight distribution will be symmetrical. Buy a 1/2" thick piece of that dense, greyish-black rubber foam at least 13" square so you can also use it for 12"s should you ever need to and cut a hole in the center about the diameter of the run out groove and big enough to expose all of the label. The label surfaces are a bit thicker and the hole in the rubber foam will have the record pressed against the top glass firmly with most of the pressure concentrated on the groove surface and run in groove area. Then let the sun shine onto it for 30 minutes. After 30 minutes don't touch anything, just put a sheet of cardboard on top that covers the entire glass surface, weigh it down in the center with some books or porn magazines or whatever and let it all cool down for at least an hour or longer. Try playing the record and see if there was any improvement. Chances are it won't yet be fixed but if you already notice a bit of improvement you won't need to add too much time for the repeat procedure or even try again under the same conditions first. The trick is to be super patient and to very slowly increase sun exposure. The exact time needed will depend on many factors like geographic location including elevation and possibly even air pollution. The thickness of the glass is crucial not only because you want to have as much weight resting on the record as possible but also to insure that the heating and cooling process are both very slow. Just the same as with good stoner rock, heavy and slow are both good things.
Be careful out there!
thanks so much, this gives me hope! i don't need to have it perfect, all i want is to get rid of the skips and slowdown effect, so I can rip it and play it from cd. won't take this to gigs anyway
