Saturday, March 29, 2014

Bromide Streaks

"Bromide streaks?"
"Why yes... yes it does."
""They should arrest it for public indecency!!"

Okay, that's a terrible joke. The truth is that if you aren't careful with your development, you could get some ghastly, ghostly streaks on your negatives. Bromide streaks, also known as bromide drag is described best by some unknown source I found on the "internet".

The developer near the heavily exposed areas of the film becomes exhausted in the process of reducing silver salts to silver. Bromide ions are also produced in this process, and being heavier than the developer, they drag downward across the surface of the film, inhibiting development in those areas and leaving streaks of uneven development, called "bromide drag" aka bromide streaking. Agitation during development brings fresh developer to all areas of the film and flushes away the bromide by turbulence within the developer."

This tends to show up for me especially on 35mm film that is developed using "stand development" (long development in dilute developers with very little agitation). It seems that the borders where the sprocket holes are provide the perfect conditions for bromide streaks. Combine that with a low contrast area of the image and you will notice the streaks of over/under development. These two photos I took at my local filling station show bromides streaks at the tops.

The solution to this problem is to choose a development method with more agitation, or use a tank that you can flip over and set down every few minutes or so. That would prevent the bromide from "sinking". So don't let bromide be a drag. Keep experimenting and you'll figure out a solution. If you have experience with this, please share it down in the comments.