I'm OCD about stuff (and I enjoy the projects) so I've worked on my own carriers over the years, solving enlarging problems as I go. I start with empty Saunders carriers for my enlarger and go from there. My latest version is for 35mm and is pretty over-the-top. I had Schneider cut the top and bottom glasses from Multi-Coated glass out of two B+W clear filters . This carrier is also to print 35mm with masks. The glass is 2mm thick.
Originally Posted by semi-ambivalent
It is possible the coated glass is also reducing Newton Ring problems. Some say yes, some say no. Either way, my fail-safe to eradicate Newton Rings is a sheet of unexposed, undeveloped, fully fixed TXP placed between the top glass and negative. Light loss is .5 stops. However with a glass carrier I'm printing at wider apertures anyway so who cares.