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LFLarry
17-Jan-2020, 21:34
I wanted to check with the group here and discuss the best methods for hardening the emulsion on large format B&W negatives?

I am in the middle of a scratched film incident, so I started thinking about mitigating methods for the future.

If you could share your technique/process for hardening the emulsion on B&W negative film, I would be grateful.

Thank you,

-Larry

j.e.simmons
18-Jan-2020, 04:48
I’ve used the various Pyrocats with x-ray film and reduced scratches.

Willie
18-Jan-2020, 06:38
Maybe process one sheet at a time and double check your handling of the negatives while you have them wet?
You give no indication as to the possible source of scratches.

Alan9940
18-Jan-2020, 06:42
Modern films generally don’t need to be hardened. I suspect it’s something in your process that’s causing scratches.

lanactoor
18-Jan-2020, 11:33
I’ve used the various Pyrocats with x-ray film and reduced scratches.

This is my experience as well. It's not magic bullet, but tendency to scratch while tray processing seems reduced.

You could employ a stop bath augmented with [chrome] alum to harden up the film. I do this when reversal processing large format x-ray. Again, it doesn't confer invulnerability, but does make the emulsion more durable.

Duolab123
18-Jan-2020, 23:19
There's many hardener formulas, Kodak SB-4 hardening bath was used in the old days for "tropical" development, i.e. above 75°F, used after the developer, rinse in water then harden for 3 minutes, then fix in a hardening fixer. This bath uses potassium chrome alum, the chromium makes it hazardous waste. Other hardeners used with older color films used formaldehyde, another undesirable.
I use good old Kodak Rapid Fixer with the hardener that comes with the fixer. Works well. Modern film indeed, shouldn't need a hardener, but it does help to harden the gelatin on film and especially on fiber base prints.

Doremus Scudder
19-Jan-2020, 12:37
... I am in the middle of a scratched film incident, so I started thinking about mitigating methods for the future. ...
-Larry

I concur with the majority opinion here: you should try to refine your handling technique before looking at chemical hardening of the emulsion.

Yes, we've all scratched a negative or two along the way, but hardening isn't a guarantee that scratches won't happen; it doesn't turn the emulsion into steel. Any wet emulsion, hardened or not, is pretty fragile. Good handling is the best insurance.

Doremus

Duolab123
19-Jan-2020, 16:07
Also development is probably where I would be most likely to scratch a negative in tray development. Hardener comes after developer. I don't like trays for film, hangers work great and cheap.