Well, frosted glass below the negative is not a good idea. As for wet mounting/oil emersion, this is a last resort at best, not something anyone would want to have as part of a normal workflow. I've tried a number of coated/thin film optical glasses in an effort to get rid of Newton rings when they occur on the emulsion side of TMax. Since it is an intermittent problem, it is difficult to say with certainty but I'm pretty sure none of them worked. The "best" solution I've found is to use a sheet of unexposed, fixed Tri-X 320, which has just enough "tooth" on both sides. But in the end, better off using Ilford. It's a shame since TMax 100 and 400 (TMY-2) are unique films. I had naively assumed there was something about the film that meant the emulsion overcoat had to be glossy. Now that I know it was simply a compromise in ease of analog workflow for the sake of scanning quality, I don't feel quite as bad about dumping them.