Some years ago I started doing more 35mm than LF and decided to also work on ways of getting as much "quality" as possible out if the small negatives. This included some DIY carrier modifications, one of which was to replace the glass with multi coated filter glass (cut by Schneider out of B+W MRC filter glass). I'm now going back to doing more 4x5 than 35mm, and started thinking about carrier glass again, asking myself the same question as when I began working on the 35mm carriers: We go to so much trouble and expense with camera lenses, enlarging lenses etc. Why then, are glass carriers made with ordinary window glass below the negative? Even expensive custom pin registered systems seem to be made this way, and when you read articles about masking and such by big name printers, nobody ever recommends anything better than window or picture glass or acrylic either. Thoughts? By the way, please refrain from posting the "it's the image that matters, not the quality" crap that often ends up derailing technical threads and causing arguments. We all know there's "nothing worse than a sharp photo of a fuzzy concept" yada yada bla bla bla. This is the enlarging forum. There are technical considerations. Accept it.