I came across a recent article by Howard Bond about the current lineup/availability of Ilford and Kodak films (as of December 2013), in which he says something interesting I had not read before:
“Ilford’s FP4 Plus and HP5 Plus (I didn’t examine Delta 100) have a welcome feature: the non-emulsion side has a minute texture similar to that found on anti-Newton-ring glass. That prevents Newton rings when a negative contacts the upper glass of a negative carrier...”
1. Is this correct?
2. Is it on Delta 100 also?
3. Is it on all formats?
4. Is this a recent thing or has it been there as long as the latest generations of these films have been around (eg has Ilford FP4 Plus always had this feature)?
For reference, the base side of Kodak's TXP sheet film has a slight "tooth" for retouching purposes, so it makes a handy anti-newton ring spacer.