A while back I asked about whether people thought adding a top-glass to my 35mm glassless negative carrier (for the Omega B66) would improve negative flatness by reducing popping. One of the intriguing suggestions was to use a piece of glass from a slide mount and place it over the negative in the carrier. I had some very old but unused/unopened Gepe slide mounts lying around. The box indicated they were anti-newton also. So after very carefully cleaning the glass I tried it. Indeed, sharpness was noticeably improved on an 8x10" enlargement. However the improved sharpness was of little use since other artifacts showed up, like imperfections in the glass, a slight texture showing on the print, and even tiny scratches. When I inspected these pieces of slide glass carefully, even before cleaning, I noticed they are really not of sufficient quality for this use. There are small surface imperfections on every piece of glass I tried, including tiny scratches, gouges etc. And the anti-newton texture is in-focus enough to show up in the print. My guess is when used as initially intended (to mount slides for projection), these flaws are probably not noticeable. Does anyone have any suggestions as to how I might proceed from here? Is there some type of higher quality slide mount glass available? Or some kind of alternative? I'm not sure how the Newton Ring issue can be dealt with either, but I feel like I should continue a little more before abandoning this top-glass idea, since the improvement in negative flatness was substantial.