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Author
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Topic: Linty Printy
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John Pytlak
Film God
Posts: 9987
From: Rochester, NY 14650-1922
Registered: Jan 2000
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posted 10-16-2004 07:36 AM
quote: Steve Kraus I was able to remove most of it by holding a velvet to the edge while winding. The material was definitely fibers of some kind. I wonder, however, if maybe it wasn't foreign matter but some defective lab equipment scraping that edge of the film and thus creating fibers out of polyester. This is not the first time I've observed this odd phenomenon.
Although a bad slitter knife can produce base or emulsion skivings, it would normally be caught very quickly by the film manufacturer's QC. And even if some bad rolls got through the system to the lab, the lab would quickly see a signal with increased shadow image dirt (the dirt particles block light during printing, resulting in a white image on the final print).
As Dominic notes, any stock or lab problem would be unlikely to affect all the reels of a print, since different equipment and even different days are involved for each reel.
When all reels of a print are affected, look to operations that handled the entire print over the same equipment. This could happen during positive assembly, or some types of print mounting or inspection operations. And of course, it can happen if a spliced print is run over misaligned rollers, or through a projector that is skiving the film edge (e.g., pinched by a pad roller, rough edge or pinched in the gate).
Quick tests for identifying film-related debris:
Gelatin emulsion will dissolve in hypochlorite laundry bleach (e.g., Clorox, Sunny-Sol).
Triacetate film base will dissolve in acetone or film splicing cement.
Polyester film base will NOT dissolve in any common solvent or water-based chemical.
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