View Full Version : Strange Green Light During Film Development

Richard K.
29-Oct-2005, 21:11
OK, I tray developed 3 sheets of 7x17 Tri-X tonight and saw the strangest thing when transferring the film from the ABC Pyro developer to the stop bath - a (fairly) bright green light under the sheet of film when first inserted into the stop. This greenish light covered the whole area underneath the film right to the edges and flared (brightened) with agitation but then petered out. I've never seen this before (although my friend Roger sees green lights that aren't there, but nevermind) and just can't figure out what caused this! The only thing I can think of is that Edward Weston was communicating to me (via the ABC) in effect saying GO, keep photographing! I've been in a photo funk lately and today was the first I've been out in months. Any ideas of what caused the green light? Anyone else ever see this? The negs came out fine BTW! (I was worried that the green light may have fogged them)

BTW, can anyone tell me how to get rid of the dark pyro stains lining the bottom edge of my formerly pristine white developing tray?

Richard K.

John Kasaian
29-Oct-2005, 21:37
Richard K:

Go with the Edward Weston story! Just make sure that no one who can get the power of attorney over your financial affairs hears about this;-)

Donald Qualls
29-Oct-2005, 23:37
Hmm. Sounds like chemoluminescence -- a reaction of something in the film (carried over developer the most likely candidate) to something in the stop bath. Was the stop bath freshly mixed, perhaps a little stronger than usual? I'd guess one of the "actinic" sensitizing or panchromatizing dyes in the film (if not already washed out in development), or just possibly an oxidation product of pyrogallol, could have been energized in some way by the acetic acid to emit a weak light -- which would look pretty bright to your deeply dark-adapted eyes after standing in the dark through presoak and development. Also remotely possible that it could have been the indicator dye in stop bath, if you use the indicator type; the color transition that occurs with the change from acidic to alkaline might be accompanied by a faint glow (release of energy), and this would occur right at the (presumably emulsion) surface of the film until the carried over developer was diluted enough not to turn the indicator, even locally (in this case, it would be more likely with nearly exhausted stop bath or a strongly alkaline developer).

I'd be curious what brand of stop bath and film you were using, just in case... ;)

I recall the first time I saw the blue light (triboluminescence) from peeling the head end tape off a roll of 620 film (after ten or fifteen minutes in the darkroom waiting my turn at the counter -- didn't think much of the teacher who brought six of us in there at once for our first attempt at loading film), I was sure my film would be fogged, but there was only a faint mark right under the tape...

To get rid of the pyro stains in the tray, hmmm... Try coffee pot cleaner? The stain is chemically similar to the brown coloring in coffee... Even full strength vinegar (5% acetic acid, or about triple strength stop bath) might lift them...

Roger Hein
30-Oct-2005, 04:49
LOL!!!! My 'green (safe)light' works just fine - but I've heard you have our own now.......

phil sweeney
30-Oct-2005, 05:37
Hi Richard,

Donald hit it on the head: chemoluminescence. Check the AZO forum, I recall this has been explained a few times.

30-Oct-2005, 05:59
Do de do do. Do de do do. You have entered the....

Conrad Hoffman
30-Oct-2005, 07:20
A related phenomena is triboluminescense- do a search on that term plus wintogreen (sp?) lifesavers!

james mickelson
30-Oct-2005, 09:28
You are not supposed to drink the stuff. I had similar things happen to me too but not since the 60's.