A12 film back scratches negatives

[ChrisBCS]

The scratches are very thin and in a group of about 4 or 5 that run the continuous length of the film, and are repeatable. They can't be seen on a light table, but are obvious in low density areas when looking at the negatives in normal light reflective light. Before I go looking for something on the rollers, is there anything obvious I should be looking for? Is there a best option for cleaning rollers?

I also occasionally am getting tiny dust spots... is it possible this is foam coming out of the light trap? Or do I just need to canned air the whole magazine? See photo of an example offending "UFO"

Y'all are the best.

 

[shutterfinger]

Emulsion side or film base side?
Does the posted photo have the scratches?
I've seen roller socket/bearing go bad and cause a roller to drag and scratch film.

 

[robrover]

Light leaks?

 

[Leigh B]

The film is only exposed (physically) and thus susceptible to physical damage in the area toward the outer shell of the A12. All parts of the insert contact the paper backing, so no defect with the insert could cause your problem.

I would remove the insert and the darkslide, then run my fingers gently around the film window at the front. You may have a ding or some dirt/detritus that collected on the inner surface.

- Leigh

 

[BMbikerider]

They may not be even scratches! Years ago there was a whole article in the UK magazine 'Amateur Photographer' about marks similar to these, and what it was causing these was concluded to be film in very dry conditions creating static electricty and sparks were enough inside the camera to cause the problem.

If it is the same mark then, no it isn't static and almost certainly some foreign body has attached itself to the Film back

 

[brent8927]

I remember buying an A12 back that caused a similar problem--scratches along the entire length of the film, just outside the frame. But it was just one long, longitudinal scratch. I think the back had some other issue because I ended up returning it, so I never found out what was causing the scratches. I did put a roll of film through WITHOUT developing it to confirm it was the back and not any of my developing reels.

 

[ChrisBCS]

Thanks guys. The marks appear to be on the base side... which makes no sense, unless it is somehow a development problem. Metallic silver deposition completely obscures them on the emulsion side.

Here are some pics of the marks where they are reflected. They are tough to photograph. Maybe post in the B&W film/chem forum?

 

[Leigh B]

The diagonal marks at the lower left of that frame did not occur in the camera.
The film moves linearly on the long axis, not diagonally.

They happened after the film was removed from the magazine.

- Leigh

 

[ChrisBCS]

The diagonal marks at the lower left of that frame did not occur in the camera.
The film moves linearly on the long axis, not diagonally.

They happened after the film was removed from the magazine.

- Leigh

Interesting. It's a wavy pattern that runs the entire length of the film strip.

 

[MattKing]

Those look like drying marks to me.

 

[shutterfinger]

I use an eyedropper of Photoflo per tank of processed film as the final step, hang the film and allow it to air dry.
I experimented to find the amount of photoflo needed to prevent water spots in my area, your water quality may require a different amount.
Squeeging film with a squeege or ones fingers can cause such faint scratches.
Is this happening with one brand of film (manufracting defect) or different brands (your handling)?

 

[Ome Kees]

Looks like streeks from dried water. The last rinse should be in real distilled water for ca. one minute.

 

[ChrisBCS]

A few notes: I use laboratory grade RO/DI water for all processing steps, start to finish. I also use photo-flo in this water for final soak before drying, a few drops per half liter.

Here's a kicker: I just looked at rolls developed using ID-11 + Ilford Rapid Fixer and these marks are absent.

The rolls that exhibit them were ALL developed in FX-39 and fixed with TF-4, and actually come from BOTH of my Hasselblad backs, an A12 and C12. Perhaps I should post this to the B+W forum? I don't have any processed using this combo that are free of the marks.

Two films have been affected: Ilford Delta 100 Pro and Ilford Pan F plus 50.

 

[ChrisBCS]

A more accurate photo of the marks, ignore my fingerprint:

 

[MattKing]

Do the marks disappear if you re-wash?
Do they affect prints?
Do you use a squeegee?

 

[ChrisBCS]

Do the marks disappear if you re-wash?

Yes.

Do they affect prints?

I haven't made any yet since getting back into film. Working on it. They don't show up in inverted pics of the negatives.

Do you use a squeegee?

Nope.

 

[MattKing]

If a re-wash solves the problem, it is a problem with your use of Photo-flo or your drying procedure.

 

[ChrisBCS]

Sorry I misread what you typed as "reappeared"

They reappear after rewashing. They do not disappear! Need more coffee!

 

[shutterfinger]

What tank and reel do you use?
What is your agation technique?

 

[ChrisBCS]

What tank and reel do you use?
What is your agation technique?

For all films both without the marks and with:

Paterson Super System 4 with the included plastic reel. Agitation is inversion. Four inversions after each minute, then rap base to dislodge air.

 

[Gerald C Koch]

Static electricity produces very distinctive marks. They appear as either stars or dendrites when the humidity is low. Since the film is essentially exposed they appear black in the negative.

 

[canuhead]

I have never seen these types of marks with any of my backs. Those are a ton of lines and I'd be hard pressed tothink of what could happen to a back to cause those. also looks like the lines are diagonal to the film direction which should rule out the back. imo, I'd be looking at processing

 

[Mainecoonmaniac]

If you process your film, do you use a film squeegee? I stopped using them. When the rubber gets old, it turns hard it scratches my film.

 

[shutterfinger]

In post 13 you state that it occurs on different films with a developer and fixer combination and not on the same make of film with a different developer and fixer combination and film from different equipment.
I suspect either ther developer or fixer in the streak combination is reacting with the plastic in the tank or reel. I would inspect the reel closely for dried chemical residue and uneven edges in the slots between the ribs.
Filter the suspect developer and fixer through a coffee filter and see if there are any hard particles in either of them.

RE post 23, skimmers that ask questions that have been answered in previous post do not deserve a responce.

 

[phass]

Here is one more theory. Do you remember if you spun rail with film CW or CCW during the final wash? Film may got off of rail and you could scratch it when you were removing the rail with loose film from tank.
Cheers.