Strengthening Film Emulsion

[Aggie]

..

[sanking]

Sandy if the pyro based developers harden, then why when he developed in pyrocat the negatives scratched and when he used the TFX-2 they didn"t?

Aggie,

It was not clear to me when the scratching took place, whether with pyrocat or with TFX-2. But regardless, even though pyrocatechin and pyrogallol harden negative emulsions they don't make them scratch proof when still wet.

Sandy

[MikeK]

Sandy:

I agree with you that the emulsion is at risk when wet, regardless of the developer. When dried that is another story

I had some home developing E6 film and getting scratches in the processing cycle. So did some experiments and found that the film emulsion was much stronger when dry (I mean much stronger).

I believe the final bath which contained formaldehyde was the hardening agent.

- Mike

[Francesco]

I agree that the negative is at risk when wet BUT why some moreso than others? Which constituents of developers decrease the risk of scratches much more than others? Just finished two sheets of film exposed similarly but developed in two different developers. One had a scratch the other did not (same developers as stated above respectively). Statistics is winning over coincidence. Chance is a powerful thing I guess.

[sanking]

I think it must be a coincidence because as far as I know the glycin in FX-2 would not harden the emulsion more than the pyrocatechin in Pyrocat-HD.

Also, someone mentioned the issue of alkalinity earlier. It is true that a very alkaline developer will result in more gelatin swelling, and this could make the emulsion more susceptible to scratchiong. But both TFX-2 and Pyrocat-HD use potassium carbonate as the accelerator and should work at about the same pH. I don't know this for sure because I have never tested the alkalinity of TFX-2. If you have a way of testing it you can compare to Pyrocat-HD which works at about 10.9.

But I am just curious. How are you managing to scratch the emulsion side of film developing in tubes? In principle nothing should be touching the emulsion side of the film to scratch it. Or are the scratches on the base side? If so, check the tubes because you might have some kind of burr on the lips or inside that is scratching the back of the film when you load and unload it.

[MikeK]

I have never had problems with scratches with 35mm or 120 roll. But sheet film is a different story. My guess is that I am at fault most of the time and most of my scratches occur when either loading or removing film from the holders.

A few years back I standardized on TMX Readyloads for my field trips. It's an age thing But while I significantly reduced the weight I was carrying, I also had the benefits of no dust spots and 100% scratch free negatives

I still use regular sheet film in all formats and every now and then a negative will get scratched. But interestingly the scratches seem more prevalent with 4x5 film, and my 5x7 and 8x10 seem to escape the problem.

- Mike

[Ole]

Found it!

The developer hardener MACO recommend is called "LP Geladur", from LaborPartner. They recommend it especially for the Genius films, which they say are very slippery and prone to damage in the developer.

I don't know if anyone sells it in the USA, nor what it is called there.