Film-Tech Forum ARCHIVE: Where did this scratch come from?

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Posted by Christopher Meredith (Member # 3767) on 08-23-2006, 06:41 PM:

I noticed some strange scratches on one of my prints a few weeks ago, then last week, I noticed the same scratches on a different print. YEsterday I was breaking down the trailer rings from one of those prints and found a section of scratched film and I am hoping someone can help me identify what caused it. It is a series of scratches, slightly curved, and perpendicular to the film. On this print they are confined to an area on the inboard side of the film but I have seen these on the outboard side as well (on a different print, however). These are confined entirely to the base side of the film which rules out platter scratces. Also, since it is only on the inboard side, it rules out a stuck roller.

Has anyone any ideas about what could have caused these? Thanks!

Posted by John Wilson (Member # 269) on 08-23-2006, 07:11 PM:

Hi Christopher

It's most likely the roller that takes the print from the wall and onto the track into the projector. Do you have hold-back tension on the platter to remove the 'droop' from platter to machine? If there's too much droop it won't get a good run into the roller and will rub on the side as you've described. Consider anothr roller between the platter and the roller in question to lift the print up to have a good run in.

What platter are you using? Can you increase the back tension on the print?

Also, from your pictures, if the scratches are on the side you are showing, that's (normally) the emulsion.

Posted by Christopher Meredith (Member # 3767) on 08-23-2006, 07:41 PM:

We use Strong platters which, as has been noted in several places on this site, have virtually no back tension. But the film pays directly from the top-most roller on the payout side of the platter to the upper guide roller above the projector head. These are all aligned such that the film sits "flush" in the roller and doesn't ride up on the flanges.

But now that I think about it, a theory has occurred to me. I have some sub-stellar projectionists and one day, I noticed that one of them was running a film with the film cleaner bypassed. But he was bypassing it to the right side (we mount them above the projector, right-side up). So the film was coming out of the upper guide roller at a very sharp angle. Perhaps this is what happened to this print? Are these scratches consistent with that sort of thing?

Posted by Charles Greenlee (Member # 3856) on 08-23-2006, 11:58 PM:

In my, uneducated, opinion, I'd suspect the take off rollers on your platter brain, or their keepers. Check this too, not as likely as the earlier suggestions, and the scratches would repeat less often, but possible. Add to it that the film was run over these rollers many many times. Also check the MUT, the rollers that twist the film along it's path may do this, durning build and breakdown.

Posted by Jesse Skeen (Member # 586) on 08-24-2006, 02:24 PM:

Scratches on film still look better than the grey-scaled NBC turkey in the corner! [Smile]

Posted by Gordon McLeod (Member # 33) on 08-24-2006, 03:41 PM:

Also I would suspect that the print was pinched between a keeper roller and the roller somewhere in the takeup path

Posted by John Pytlak (Member # 331) on 08-25-2006, 10:57 AM:

Although more severe and numerous than I usually see, they could also be "platter scratches" where the film was not guided properly onto or off the surface of the platter, allowing the rotating platter surface to rub against the surface of the print.

Posted by Manny Knowles (Member # 1171) on 08-26-2006, 01:41 PM:

I'm with J.P. on this one. Looks like bad plattering to me.

Posted by John T. Hendrickson, Jr (Member # 849) on 08-26-2006, 03:56 PM:

Here's another thought. The large roller on the lower arm of the projector will sometimes wear down if it is made of plastic. Depending on the angle that the roller is set at to accomodate the passage of film from the failsafe, across the roller, and back to the platter, plastic rollers will wear down on one side and cause the very scratches you show in your picture. Incidently, I also have Strong platters.

When I discovered the same type of scratching, I pulled a number of these plastic rollers and replaced them with nylon rollers. End of problem. Wish I had saved one of the old ones for a picture. One side was badly worn and causing those annoying faint scratches.

I've had no problem since replacing those plastic rollers, so you may want to check yours.

Posted by Brad Miller (Member # 2) on 08-26-2006, 11:50 PM:

It is important to know if the angle and curvature of the scratches change from the first trailer to the end of the feature. That will tell us if the scratches came from a misaligned or misthreaded roller vs. on the platter takeup.

Posted by John Wilson (Member # 269) on 09-17-2006, 08:51 PM:

Hey Christopher

Any success on finding the reason to this one?

John