Thomas, TMAX films and Acros can sometimes be tricky - in fact with these films you can sometimes get Newton rings even on the emulsion side because the emulsion is comparatively glossy. I've actually been corresponding with John Sexton on this issue regarding experiments each of us have been doing with a variety of different coated glasses. It has been an interesting project so far.

Anyhow - if you get the occasional problem on the base side (the usual place Newton rings show up), and you don't want to start messing with all sorts of fancy glass - a lot of the anti Newton rign glasses out there are crap - here's a simple trick I came up with, which I've posted about before:

Cut a piece of fully fixed, unexposed, undeveloped Tri-X 320 and sandwich it between the top glass and the negative. Since the base side of Tri-X 320 is designed for retouching, it is just rough enough (as is the emulsion side) to eliminate Newton rings under most circumstances. It works very well. There is light loss of about 1/2 stop. Hope this helps.