What the...! Luminous tape on 120 film?

philosomatographer · Sep 15, 2009

Alright, explain this to me: My technique for developing 120 film is to first roll up the film (away from the backing paper) and then of course peeling off the tape from the film, before spooling it for development.

Today, I took a closer look when peeling the tape (my darkroom is really, really dark - nothing can be seen whatsoever even after 30mins) and, when peeling the tape, it became luminous! As the tape was being pulled off the film, the specific part being separated from the film at that moment emitted a clearly visible glow (similar to static electricity, although not clearly defined spark - just a glow of sorts, I could have sworn it was blue).

Any possible explanation, or has anybody else ever seen this?? Next time, I will try to pay attention as to whether this fogs the film (of course, it would not be a concern, as this is on the un-used edge of the film).

I am flummoxed. I'd love to show you, but I think I'd need a DSLR that goes to ISO 25600 and an f/1.0 lens to capture this. But it's there...

keithwms · Sep 15, 2009

Static. It's quite a common occurrence with any tape. I see it all the time In practice it's not a problem because the tape isn't directly adhered to the film. I haven't seen any fogging from it. By the way, you also see this when you open photopaper...

tim_bessell · Sep 15, 2009

static electricity --- just like you said.

Sirius Glass · Sep 15, 2009

Keith got it first ... static electricity.

Now you can unflummox!

Or is it deflummox?

Steve

AgX · Sep 15, 2009

But there is also tension-luminescence.

RalphLambrecht · Sep 15, 2009

I'm with AgX on this. It's common, it's normal, it's harmless, but it isn't static.

It is the adhesive in the tape. Some of the energy you put in by peeling it off is released through tension luminescence in the adhesive layer.

Aurum · Sep 15, 2009

Yank it hard enough and you might give yourself an X-Ray

http://physicsworld.com/cws/article/news/36357

Though admittedly they were cannoning that roll of scotch tape through the machine at quite a rate of knots

Sirius Glass · Sep 15, 2009

philosomatographer said:
Alright, explain this to me: My technique for developing 120 film is to first roll up the film (away from the backing paper) and then of course peeling off the tape from the film, before spooling it for development.

Or you could just fold the tape over the file because there should be no latent image there. Process the film and then just cut off the tape when cutting the negatives.

Steve

bdial · Sep 15, 2009

What they said.

You can just tear the tape at the line between the tape and the paper, but leave the tape on the film. I find the extra stiffness helps a little in getting it on the reel (stainless ones, anyway).

fschifano · Sep 15, 2009

It's called triboluminescence. See this wiki

keithwms · Sep 15, 2009

Oh I see, so it's not just an ordinary static discharge. Good to know.

Banging sugar in the darkroom is something I have done, that is quite cool.

mwdake · Sep 15, 2009

I have seen this also, only once I think or only once that it freaked me out.
It was almost like some shone a bright flashlight right just for a split second.
I can't say I saw any ill effects on the film but I wouldn't like to go trying to do it everytime.

mike c · Sep 15, 2009

I use to see that glow alot back a few years ago,don't see now.Maybe Kodak changed there tape or my eye sight is getting worse.

fschifano · Sep 15, 2009

I haven't seen it lately either. Black electrical tape used to do this too. In any case, it's not bright enough to have any visible effect on the film.

polyglot · Sep 15, 2009

I haven't observed this directly because I use a dark bag, but I will note that when using Acros in 120, the film directly under the tape is spottily exposed. Fuji seems to use plastic tape whereas Ilford films (with papery tape affixing them to the backing) aren't exposed at the ends.

philosomatographer · Sep 16, 2009

Thank you all for the very informative discussion. I had my suspicions that this is not static, so thank you for the info and link regarding Triboluminescence. Amazing what one learns every day...

Ross Chambers · Sep 16, 2009

fschifano said:
It's called triboluminescence. See this wiki

Now THAT I'll file away for use next time (or more likely, if ever) I need it for a TV Quiz show. Indeed one does learn something every day.

I have seen it once when peeling with vigour, these days I'm slower all round.

Regards - Ross

Alex Bishop-Thorpe · Sep 16, 2009

Ball lightening, clearly.

But, that's just plain cool. Thanks APUG, for answering questions I never thought of asking.

nick mulder · Sep 16, 2009

Can cause havoc with old (old) 16mm film running at high speeds (you dont need tape, the film itself does it, right on the emulsion) - a mates 30 year old FP4 had this issue even at 24fps and I have seen it on 20 year old PlusX but that was at winder speeds, nothing that a camera would produce...

George Collier · Sep 16, 2009

I fold the tape over, and load the reel from that end. It gives the little clip something else to hold onto.
Also, since I always load that way, it helps to diagnose problems with processing.

ic-racer · Sep 16, 2009

I started always cutting the film because I observed this discharge about 30 years ago and it would fog the film. Recently, though, I noticed if you peel the tape slowly you can be OK. This pertains to re-spooling 120 to 620 rolls, where you need to release the tape and re-stick it.

bill schwab · Sep 16, 2009

ic-racer said:
I started always cutting the film because I observed this discharge about 30 years ago and it would fog the film.

Interesting as I have never had a problem with this phenomenon fogging my film in any way. I wonder if this is due to your local conditions somehow making it worse.

AgX · Sep 16, 2009

That however would indicate a static-electricity phenomenon.

fschifano · Sep 16, 2009

ic-racer said:
I started always cutting the film because I observed this discharge about 30 years ago and it would fog the film. Recently, though, I noticed if you peel the tape slowly you can be OK. This pertains to re-spooling 120 to 620 rolls, where you need to release the tape and re-stick it.

Could be stress fog too. Take a piece of unexposed film, and put a crease in it. Develop the film. Bet you see some fog along the crease mark.

mike c · Sep 16, 2009

fschifano said:
Could be stress fog too. Take a piece of unexposed film, and put a crease in it. Develop the film. Bet you see some fog along the crease mark.

I call those artificial moons,happens when I careless or just plane clumsy loading film on the reel .

What the...! Luminous tape on 120 film?

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