Why are records still warped?

WPC- Thanks for the information which explains this issue very well.

OP here - + 1 to WPC. A thorough and exact explanation of why it still happens with such alarming regularity. Thank you.

Also, I appreciate Lowrider's input. I knew there also had to be a business philosophy behind the bad attitude. Losing money sure makes folks cranky.

Perhaps I'm missing something, but I own many, many a flat record, some decades' old. Unless the polymerization process is a brand new phenomenon, which it shouldn't be, the thread question still stands and WPC's explanation is an interesting piece of information, but not much more than that. I think Bdp24 hit the nail on the head 2 months ago.

I did not mean to imply that very flat records aren't possible, in fact, by far the majority of records produced now and back in the day are flat. I was trying to explain the challenges involved. Molecular weight distribution at the end of the bell curve create the problem. As said, longer cycles and modern machines will improve the odds. In addition, using well maintained older machines and processing techniques that minimize oxidation and hydrolysis (which break molecular chains further exacerbating molecular weight variation) can improve the likelihood of a precision outcome. Finally, a 100% QC inspection process will obviously eliminate those warped records which occur when initially produced (but those aren't the problem)

I am certain some record suppliers do a better job than others but zero defect production is much more difficult than Bdp24 implies. Some records still warp even when left in the press long enough to come out flat and when packaged and stored properly . A small percentage will warp down the road because the molecules in that particular shot of material happened to all have lengths at one end of the distribution range (be it long or short) which completely changes the rheology of the flow of the material which changes the internal stresses. They go into a sleeve perfectly flat and change in the days and weeks to come.

This is an entirely different challenge than faced by manufacturers in the metals businesses (machining, casting, edm, etc.).

Bdp24
New LPs are warped either because they were removed from the LP stamper before they had cooled sufficiently, or because they were not transported and stored properly after they left the pressing plant, or both.

The record labels and the pressing plants all say that demand is so high for manufacturing vinyl that their orders are backed up. There was a thread on Steve Hoffman, I believe, where somebody stated that the cooling stage had been shortened as one way to speed up the process. I'm sure there are other areas where vinyl production specs don't measure up to the original days of record cutting. Especially quality control as previously mentioned.

On a personal note, I returned "Mothership" 3 times to Amazon all with the same problem...a clicking sound thruout side one. It would seem an entire batch of product was shipped out w/o being checked.

" A small percentage will warp down the road because the molecules in that particular shot of material happened to all have lengths at one end of the distribution range (be it long or short) which completely changes the rheology of the flow of the material which changes the internal stresses."

Makes a lot of sense as far as new vinyl or the original cutting days.