Argenti RapiFix - anyone used it on T-Max 400 or any other film?

"RapiFix is a universal fast-working acid-based fixer suitable for all silver-halide B&W photosensitive materials"
Goes on to say you dilute at 1+4 and its 1 min for film....
If im gonna use it on T-Max 400 then how long should I fix for???????????

From your description, it sounds like just another run of the mill rapid fixer, and 1 minute isn't going to do it for TMax. Take the trimmed off leader from the film if you have it and dunk it into the fixer. See how long it tales to clear. Double or triple that time and you have it. If not, five to seven minutes should be more than enough with fresh fixer.

The Tmax films I use do take longer in fresh fixer to clear,also a little more washing.

Frank you say "trimmed off leader" - I have a roll of 120 that i sacrificed in order to show a friend how to load a film on a roll will that do? see how long that clears?????

If it's the same kind of film, yes. Be aware that different films have different clearing times. For example, Foma films will clear within 30-40 seconds in fresh rapid fixer. Kodak's Tri-X can take 2 - 3 minutes. TMax a bit longer still.