Base fog on batch of HP5+

I have a batch of 35mm and 120 HP5+ that all has heavy base fogging and I'm somewhat baffled about how it happened.

I had a number of mixed 35mm and 120 rolls of FP4+ and HP5+ from a recent trip. I processed the FP4+ in D76 1:1 in a tank that holds 8 35mm reels. It looks great. I then processed the HP5+ in Rodinal 1:75 with sodium sulfite (a dilution/combination I've used for 30 years with excellent results), same tank, and all that batch has a heavy base fog.

The 120 HP5+ is out-of-date. It expired in 04/2006 but it was kept frozen until sometime last year. The 35mm HP5+ expiration date is not until 11/2007. Both films were equally fogged--no pattern like it was exposed, just a lot of uniform fogging of the film base.

Rodinal usually lasts for years. Sodium sulfite was bought within the last year and it probably never goes bad as long as it's kept dry.

I'm planning to run some tests this weekend but I was wondering if anyone has any ideas????

I processed HP5+ in D76 1+1 and had the same experience with fresh and outdated film. As far as I'm concerned, it is just normal for HP5+ and causes no real issue. I've seen some recipes to remove the fog but never saw a reason to do so.

The base density of unexposed, fixed HP5+ is about 0.3. I think the purpose is to prevenyt light piping and is only used in 35 mm where the leader can pipe light quite a distance down the film base, just like a fiberoptic filament. Other 35 mm films either use a lower base density or a dye in the gelatin beneath the sensitive layer. Slower films, like FP4+ do not need as much base density for that purpose.

I develop HP5+ in Rodinal 1+60 with Borax added @ 1 gr./ L work-solution (thank you Patrick Gainer !!) for 18 min @ 20°C (E.I. 400 ASA) and I am happy with it. Less base fog than processing in X-TOL stock! Nice tonal values an a 'present' but, to my very personal opinion, 'aesthetically acceptable' grain.
As a matter of fact, I do like grain, not to much yet just enough, because it is an essential and a natural part of the emulsion (by this characteristic for analogue work).
This is why I really do not understand all this hassle about grain. It is so inherent to silver based photography. All emulsions have, more or less, grain, so respect it and use it instead of 'hiding' it.

'Good' (*) grain must be!

Good Luck,
Philippe

(*) In this context, 'good' is, of course, a very personal value and can only as such be defined.

I appreciate the information but....This is the first time this has happened to a batch of HP5+ in the many years I've used it with the same developer.

Comparing these negatives to the thousands of others I have on file, this is something new.

I would have thought it was the out-dated 120 film except for the fresh 35mm processed in the same solution.

The fact that the 120 film also had high base density indicates that something was wrong with either film or process. I did have part of a new bulk roll of HP5+ so fogged I couldn't use it, but figured something had happened between the bulk loader and the developing. Maybe not. The rest of the bulk roll has been fine. There are numerous things that can fog film, including X-ray inspection of packages. Who knows?