Light leak in film holder or bronide streak?

[brian steinberger]

I just ran a batch of 6 sheets of HP5 4x5 in a half gallon tank with kodak hangers in ID-11 1:1. I agitate continously for the first minute and then ten seconds every minute. I agitate very gently, as I've had problems with bromide streaking in the past.

One sheet out of all 6 had a denser line on the top. I'm leaning towards it being a light leak, because wouldn't all 6 sheets have the same density line in the same area if it were bromide streaking? All the other sheets were fine.

Besides the answer being either way, how can I test my film holders for light leaks?

[rwyoung]

I would test the holder by loading film and placing them in direct sun for a few minutes, darkslide closed of course. Then to develop, if you aren't secure in your developing abilities or chemistry condition, mix up FRESH chemistry from commercial stock (ie the yellow bag or a new white bottle). Use about 1/2 tray full (5x7 tray), then in the dark, add your film and make sure it is fully covered, emulsion side up. Once every minute, gently lift each corner of the tray. After 7 minutes (a bit overdeveloped) lift out sheet, place in water bath for 1 minute with gentle rocking. Move to fixer, gentle rocking for 3 minutes before you turn on the room lights.

If you are generally confident in your developing abilities and chemistry, then develop as normal.

To test for streaking during developing, use unexposed film from the box. Sacrifice two sheets, put on in the hanger "normally", the other turned 180 degrees. If you get streaks in the same place on both relative to the hanger, it is technique or equipment. If the streak appears in the same place relative to the film (ie opposite sides relative to the hanger) it is damaged film.

[Glenn Thoreson]

For testing film holders, I use paper. It's much more economical. If the holders are OK, then use film to check your development method for flaws.