Developing Rollei RPX

[joeswe]

I do not have a problem with consistency, I was only wondering about the completely different development time recommendations for the rollfilm version and the sheet film version of the current RPX400 (18 min vs. 12 min in Xtol 1+1). I wanted to use a film in 4x5" that I am already familiar with from smaller formats, but when I saw the different times I was asking myself, is this a typo or does the sheet film use a different emulsion that is just be labeled as "RPX400" for marketing reasons, to have a complete line-up from 135mm to sheet film?

I have contacted Maco/Rollei in the meantime and got a reply that the much longer development times are due to the different base (PE) of the sheet film version (120/135mm have acetate base). I am not sure if I should believe the base can really make such a difference in development times. 😕

 

[Fotohuis]

I am not using RPX 4x5" sheet film so I can not give any further info on this. I only know that Harman/Ilford production in 35mm and 120 roll film is always done on 135um/100um tri-acetate , sheet film 175um where Foma is using tri-acetate for 35mm and 120 roll film on Clear Polyester (100um) and sheet film on 175um. Agfa Gevaert aviation type films are always on 100um Clear Polyester layer so both for 35mm and roll film the same E1 (stands for 100um) type. The S stands for Synthetic (=Polyester) in the Retro 80(S) and Retro 400(S) and IR-400(S). So here the problem that the IR-400(S) in sheet film is very thin (100um) so more difficult in handling.