Well if it isn't temporary, I haven't noticed - the records seem to lie just as flat. I've noticed sometimes they seem to lie flatter...more relaxed, as though the tension in the vinyl that was causing the warp was reduced.
Perhaps it comes down to technique. I'm not steaming the record 'dry' - I'm steaming it when it has a layer of solution or water on the surface to take up the heat. All the steam jet seems to do is shake things a up a bit. At the distance I spray from (6-8 inches), the steam is almost cool to the touch. Makes me wonder about the antiseptic claims on the steam cleaner infomercials.
I guess calling it steam is a misnomer. Actually, it's just hot water you're squirting on the record. Probably in the 130-140F temperature range.
I've seen some of the youtube vids of the use of steam, where the record warps considerably when the hot water is applied. Yes, then it appears to relax, and flatten after the heat is withdrawn.
What effect this stretching-contracting of the record imparts to the surface of the vinyl, I have no idea?
Generally, if the cleaning product is good, "shaking things up a bit" usually can be adequately accomlished with a good quality cleaning brush to agitate the solution on the record.
What I do with any of the AIVS cleaning solutions (#15 pre-cleaner-enzymatic, or super cleaner), is I apply, insure complete coverage of the product to the vinyl, with the applicator brush, with absolutely no downward pressure, then let the product sit a number of minutes. Generally about 4-5 minutes is good in most average cases.
Only after that period of sitting will I then begin to do an agitation of the fluids on the record. Again, I do not apply any downward pressure on the Brush-Brush Pad. By pressing down, this flattens the bristle of the brush, and probably lessens its effectiveness. It also raises the chances of placing a greater degree of micro-scratches into the vinyl. The dirt in fluid suspension then can act like an abrasive slew.
I liken it to taking a concours automobile through an auto car wash, or hand washing it. The hand washing of course is going to be more gentle, and less likelyhood of deeply scratching the finish, correct?
I feel the same holds true with the record. A gentle touch is always best. It is important with any cleaning product you use, no matter if DIY, or commercial.
It was another reason why I favorably selected the VPI 16.5 RCM, in that I can totally control the degree-amount of pressure of any cleaning brushes used upon the record.
Giving those products the proper time to do their jobs is a key element.
Ther importance of a final rinse is something I cannot stress enough. Mark