Film-Tech Forum ARCHIVE: Cross Scratching

This is topic Cross Scratching in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Jason Wharton (Member # 5168) on 03-14-2009, 05:49 PM:

Hi guys, i'm new here and have a quick question for those of you more knowledgeable than myself.

Basically, i've had a couple of incidents of cross scratching appear at my cinema and I know of the obvious causes for this and it is more than likely that it was human error when running on or lacing up. My question is though, is there any other way cross scratching can happen?

I only ask this as someone once mentioned to me that an intermittent unit on it's way out can cause it, seems bizzare to me but does anyone know if thats the case?

I know this is probably a dumb question, I am in the position where I never really recieved any propper formal training and what I know is what i've picked up over the years i've worked in the booth and i'm always looking to improve my knowledge.

Anyway, thanks in advance for your help!

Jase.

Posted by Boris Brown (Member # 5069) on 03-14-2009, 06:51 PM:

Hi! It seems to me that the intermittent unit isn't the cause of the cross scratching. It's most likely that it is the 'incorrect' movement of the film through the projector or platter (if there is one).
Good luck!

Posted by Ken Lackner (Member # 1002) on 03-14-2009, 06:56 PM:

Hi Jason. Welcome. You will find many knowledgeable people here eager to help. Don't feel ashamed to ask; a closed mouth never gets fed, so to speak. That being said, right now we don't have much to go on. Please list what equipment you are using so that we can pinpoint the problem. Platter, projector head, sound head (analog and any digital heads that may exist), failsafe, and anything else that may be in the film path. Furthermore, what do you mean by "cross scratch"? I've not heard this term, but to me it sounds like a horizontal scratch across the image. I don't see how an intermittent could cause that, so that may not be what you are trying to describe.

With a little more info, I'm sure someone here will be able to help you get to the bottom of it. Cheers! [beer]

Posted by Gordon McLeod (Member # 33) on 03-14-2009, 07:11 PM:

Almost every case of cross frame slashes can be traced back to the film be on the flange of a roller or pinched over the flange of a roller by the keeper

Posted by Ian Parfrey (Member # 5122) on 03-15-2009, 06:18 AM:

...or film rubbing against the flange of a spool or against the platter decks.

Posted by Gordon McLeod (Member # 33) on 03-15-2009, 08:11 AM:

Ian said "...or film rubbing against the flange of a spool or against the platter decks. "
I aways tend to discount that one as it could only happen due to a misaligned roller that would always happen on every time that deck was used

Posted by Jason Wharton (Member # 5168) on 03-15-2009, 10:43 AM:

Hi again and thanks for all the replies, I'm pretty sure this was human error, and it's happened a couple of times, I just don't wanna point the finger at someone and it actually be the equipment at fault.

Platters are christie AW3's, Century SATA heads, kelmar analogue/digital soundhead, strong fp-350 optical failsafe/pulse reader.

And by cross scratching I mean multiple horizontal lines accross the frame, in this particular case on the emultion side of the film.

Posted by Bruce McGee (Member # 131) on 03-15-2009, 11:51 AM:

We recently had a print with scratches like this. One of my 'operators' misthreaded the AW3 and the film was dragging across the platter itself on take-up. The very edges of some of our decks are a bit rough, and this is where our horizontal scratches came from in my case.

Posted by Jason Wharton (Member # 5168) on 03-15-2009, 12:21 PM:

this is exactly what I think has happened on this occasion, trouble is I can't pin point it to one technician as it happened while I was off.

Posted by Mike Blakesley (Member # 26) on 03-15-2009, 01:42 PM:

quote: Bruce McGee
dragging across the platter itself on take-up.

It can happen during buildup or teardown too. If you have a movable roller on the MUT and it is positioned such that the film is dragging on the edge of the platter, scratches across the film will result. This can happen very easily on the Christie AW3.

Posted by Jason Wharton (Member # 5168) on 03-15-2009, 04:34 PM:

Yeah, I was aware of that one ;-) The film was rehearsed before showing to the public and the scratching wasn't there so can only of happened sometime during it's run.

Posted by Jim Cassedy (Member # 4115) on 03-16-2009, 09:05 AM:

The only time I've seen "hash mark" horizontal scratches on
a Christie platter is when the film is rubbing on the edge.

STRONG platters can put short diagonal hash marks if the
brain is threaded wrong. It happens at my theater when
someone is in a hurry. The film rubs against one of the
guide rollers around the circumference of the brain and
the roller flange puts short horizonal marks on the film

ILLUSTRATION- (Using a 70mm Brain)

It's easy to do it wrong, especially on the middle or
bottom platter if you're in a rush and/or get distracted.

I've heard of some people totally removing that roller.
I figure it's there for a reason so I just make sure I
double check the film path from the platter to pole.

Posted by Justin Gorka (Member # 3727) on 03-17-2009, 01:10 PM:

You have a technician who can't lace up properly?