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New MP scratching negatives


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My MP has begun scratching negatives. The scratches (2) are outside of the frame and run the entire length of the film, at the top (bottom of the gate) and between the sprocket holes and the edge of the image. Every roll of the last 9 or so but not any prior to those. It appears to be in the emulsion; under a magnifier the line is dark and comprised of grain, but looking at the negs on a light table it looks like it's dark by refraction.

 

This could just be a bur on the film rail but I would think that would have shown up from the first roll, but it didn't. Can't see anything obvious and the pressure plate feels fine. Would it be wise to give the rail a single gentle wipe with some 600 grit emery cloth? Or see if the film wears it down over time? Certainly not the end of the world, but an annoyance on an otherwise wonderful camera.

 

thanks,

s-a

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That's not a happy start, but all can be solved. Soon I hope.

 

have you inspected the film path closely, presumably you have. Try shaking the body, there may be a loose screw that has fallen into the film path (long shot I know).

 

Are all the scratched films from the same batch. It could be a manufacturing accident. Try a different brand of film to eliminate that possibility (another long shot).

 

Could the fault be a processing problem? Are you processing or sending it out? Try another processor.

 

It is possible some detritus has crept into the back when inserting a film cassette. A bit of dirt may be lodged in the cavity where the film slots in. Try a good blower brush to clear the general film path.

 

Sorry, running out of ideas.

Edited by erl
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That's not a happy start, but all can be solved. Soon I hope.

 

have you inspected the film path closely, presumably you have. Try shaking the body, there may be a loose screw that has fallen into the film path (long shot I know).

 

Are all the scratched films from the same batch. It could be a manufacturing accident. Try a different brand of film to eliminate that possibility (another long shot).

 

Could the fault be a processing problem? Are you processing or sending it out? Try another processor.

 

It is possible some detritus has crept into the back when inserting a film cassette. A bit of dirt may be lodged in the cavity where the film slots in. Try a good blower brush to clear the general film path.

 

Sorry, running out of ideas.

 

Thanks for the post erl.

 

I bulk load a couple different emulsions and they're both showing the sympton. I've checked a foot of one of them off the core and it's clear. Imagine the other would be too. This is also across 10 cassettes so I've ruled those out. I process myself and maintain what I think is pretty good technique. In any event the scratch is not in any area that is touched by the reel's spiral (Hewes). I do not use a bulk loader but spool loose film in the darkroom. I'll bend a fluffy pipe cleaner into some kind of sweeping tool and see if I can dislodge anything from where the film goes under those bridges at either end of the film gate.

 

Thanks!

s-a

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