potassium bromide as anti-fog for negatives

[Auroraua]

Just thought I should post my result.
Think it is still heavily fogged and I thin they photos are over exposed, shot it at 50 ASA.
It was an Orwo NP20 film.
Rodinal 12min
20C
Added 1 ml of a 2% potassium bromide solution. Think I should have tripled that.
http://www.flickr.com/photos/104979973@N04/tags/orwonp20/

 

[Bill Burk]

Athiril, I think we just mixed up developer speed and emulsion speed. I was talking about the latter, and Bromide is unlikely to increase it. I have no opinion about developer speed.

As I try to figure what the discussion is... I think more likely the idea being mixed up is emulsion speed... of the fogged film... which has already been lost.

I've got some expired Tri-X which I rate at EI 64 because that is the exposure required to see 0.1 above Base+Fog.

What would be the speed of that same Tri-X developed with some Potassium Bromide in my D-76 1:1?

I'm not going to get 400 no matter what I do.

If the Tri-X was fresh, yes, I would lose speed, it would no longer be 400.

But it's possible that my fogged Tri-X would be fine at 64

 

[Rudeofus]

Added 1 ml of a 2% potassium bromide solution. Think I should have tripled that.

1 ml of Sodium Bromide 2% contains 0.001l * 20 g/l = 0.02 g. With a 250ml batch that's less than 0.1 g/l Bromide. The first minute of film development will put more Bromide into solution than this miniscule amount. You will haver to increase that amount at least ten or twenty fold before you will see a difference.

What would be the speed of that same Tri-X developed with some Potassium Bromide in my D-76 1:1?

I'm not going to get 400 no matter what I do.

Not all hope is lost, and Bromide is not automatically evil. If you look at color developers, they contain Bromide and even Iodide, yet reach full emulsion speed. The main question is whether you have enough expired product so you can fine tune your developer.