A challenge to the finest minds in LF: The ghost image

[Natha Congdon]

Here is a problem that really has me stumped! My hat's off to whoever can figur e this one out.

I recently acquired some Sinar adhesive 8 X 10 holders. Though not new, they ar e from a reputable source. Whatever image I shoot with these, all four shots in 2 holders come out with a very obvious branching or arborizing pattern. This i s not subtle! It looks as if I had made a double exposure with a forest shot, t hough I definiely did not. Shots made interspersed with other holders have no s uch ghost images. Though similar, the placement of the images is different on s hots from each holder. Is this:

1. A chemical reaction of the adhesive to the film? Perhaps the original adhes ive degraded over time, or was replaced? (But close up, these really look like TREES, more than a chemical fractile-like pattern).

2. Emulsion from someone's old shot where the film was inadvertently loaded wit h the emulsion facing the adhesive (Could explain the similarity of patterns fro m the different holders: a full day of shooting in the forest with film loaded backwards in all the holders?)

I have to admit these sound pretty far-fetched! But I have no doubts at all abo ut what I'm seeing. I suppose I could keep shooting and see if the problem slow ly goes away, but I'm not keen to waste that much HP5+! I will contact Sinar an d the seller, but I thought that some of the resident Great Thinkers on this for um were my best bet. I would be very grateful for an explanation, and a practic al solution would be True Nirvana!

Thanks in advance,

Nathan

[Natha Congdon]

Addendum: For whatever it's worth, these are all HP5+ negs tray- processed identically in PMK pyro (80 degrees, 8 min), one sheet per 11 X 14 tray.

Nathan

[Sean Billy Bob Boy yates]

Just to check, have you made more than one exposure with each side of each holder? If so, do the patterns match from negative to negative - i.e. two negs from the same side of the same holder held together on the light box?

Could it be that the adhesive is getting old and has lost some of it's tack? Or rather - retained tack on the film side but lost it on the holder side? Then residual adhesive on the film is lost during developement?

If not, then it could be part of your loading procedure - uneven contact with the adhesive? What about your shooting conditions - are you loading indoors and then shooting outdoors? Could it be condensation between the holder and the negative?

If the emulsion from someone's previous negative was left on the holder platten - wouldn't you see it?

[Hans Berkhout]

? Electrical discharge?

[Paul Schilliger]

Very mind-boggling! I would second the idea of a static electricity problem. Wh en loading and unloading the films, try to make everything very slowly to avoid the static discharges...? I have not iced the small "lightenings" too when loading/unloading 4x5 holders too quickly. The large size negatives can only enc rease the risks. If the air is very dry, the problem can be quite bad although I had never noticed anything on my low sen sibility color slides. The arborescences should be darker (exposed) on your negatives.

[Wayne_6692]

Is it a chemical reaction with/coating of the anti-halation backing of the film that you are using prventing the clearing og the backing? If not I vote for static marks.

Wayne

[Struan Gray]

I'll bet it is 'triboluminescence', light produced by quite a few polymers and inorganic materials when rapidly stressed. 'Wintergreens' are supposedly a US candy which does this when bitten into, and the adhesive at the end of most 120 roll films will also show the effect if you tear the backing paper from the film fast enough.

I can't believe that Sinar would be daft enough to use an adhesive which luminesces enough to fog film. Perhaps your source has renewed the tackyness with an unsuitable adhesive?

[Julio Fernandez]

Nathan: When some adhesive tapes are released from the substrate in the dark, light can be seen to be released. I always thought this was caused by static electricity; friction or energy between static prone materials always causes static electricity that can cause such sparks. Struan indicates 'tryboluminescence', he probably is right, I was not aware of that phenomenon. Of course, Sinar should have tested the adhesive and of course, this did not happen at Halloween?

[dave bulmer]

I had a similar experience in the darkroom whilst ripping the tear-off strip from a new pack of Ilford multigrade paper, a large firework display of green light from the glue! whilst trying to replicate the dispaly recently nothing happened so Ilford must have caught on.

[Doug Paramore]

Nathan: I really shouldn't be answering your question since you wanted an answer from the finest minds in LF. I certainly don't fit in that catagory. However, I would go along with the static electricity theory. It wouldn't take much of a discharge with the film in contact with the adhesive. It is possible that the adhesive has been renewed with one that produces a current when the film is removed. Since the pattern appears to be tree branches, that pretty well confirms the theory of static charge. I suspect it occurs when you remove the film from the holder.

Regards,