Why Are Pyro Negativess So Delicate, Easily Damaged?

[Andre Noble]

Why are Pyro Negativess Delicate, and What to Do About It?

I noticed that both my sheet film and roll film pyrocat HD negs (water stop, TF-4 fix) are easily suseptible to physical damage. The 'easily scratched' part I understand as there is no hardener in the process per se. But what I don't get are the tiny (and not so) approximately circular flakes of missing emulsion on random areas of post-processed pyro negs.

Anyone else notice this tendency? Any solutions? Does anyone has a formula/product to recommend for hardening pyrocat negatives?

[Jay DeFehr]

Pyrogallol and catechol actually harden the emulsion through tanning. Pyrocat-HD works at a high pH, which swells the soft emulsions of EU films like Efke, Foma, or J and C Pro 100, etc., making them vulnerable to mechanical damage in handling. Switching to a rapid, hardening fix will help, but might cost you some stain, or it might not. Keeping processing temps low will help, but not as much as switching films to a modern, hardened emulsion, or switching developers to one that works at a lower pH, and hardens the emulsion, like 510-Pyro, or both. Good luck.

Jay

[Paul Moshay]

Are you using an acid stop bath, that can cause that type of problem, try using a plain water rinse before the fix. Paul

[Doremus Scudder]

André,

I would agree with Jay that the high pH of Pyrocat in combination with soft-emulsion films is probably the culprit. If you are using Bergger film, or one of the ones that Jay mentioned, then you must be very careful when handling them, especially the sheet film if you tray develop. Also, as Paul mentioned, a strong acid stop in combination with a high pH can cause gas bubbles to form in the emulsion. However, you mention that you use a water stop and TF-4, so that is not your problem.

I used a lot of Bergger film with a similar procedure to yours and had to be extremely careful with handling. Tri-X processed the same way was much more sturdy.

Some possible remedies: presoak your film if you aren't already to minimize the speed of the swelling when immersing in the developer. Reduce the intensity of the agitation a bit. Try to keep wet-time to a minimum; emulsion flakes can happen if the soft emulsion is wet too long.

If none of the above work, and you don't want to change film, do what I did: Use a weak acid stop and switch back to a non-hardening slightly acidic fix (Ilford Hypam, etc.). This lowers the pH environment of the film and prevents so much swelling of the emulsion. If all else fails, switch back to a film with a pre-hardened emulsion such as Kodak or Ilford.

Best of luck

[Andre Noble]

Since I'm encountering this problem while using a water (not acidic) stop bath, and Ilford FP4+ film both roll and sheet film, I will look to the non film-choice solutions suggested above. Thanks.

[sanking]

Why are Pyro Negativess Delicate, and What to Do About It?

I noticed that both my sheet film and roll film pyrocat HD negs (water stop, TF-4 fix) are easily suseptible to physical damage. The 'easily scratched' part I understand as there is no hardener in the process per se. But what I don't get are the tiny (and not so) approximately circular flakes of missing emulsion on random areas of post-processed pyro negs.

Anyone else notice this tendency? Any solutions? Does anyone has a formula/product to recommend for hardening pyrocat negatives?

Some of the East European films, Efke in particular, are very prone to physical damage during develoment, whatever the developer. Pyrocat-HD, and other pyrogallol and pyrogallol developers, actually harden the emulsion and keep it from swelling more than non-tanning developers such as D76 and Rodinal. The solution is that if you choose to use these films you must be very careful in handling them. I would recommend rotary processing in Jobo or BTZS type types rather than tray processing as you are much less likely to damage the film with this type of development.

As for stop bath, I recommend an acid stop bath of about 1/2 strength for Pyrocat-HD negatives. The diluted acid stop bath will not cause any loss of proportional image stain.

Sandy