Film-Tech Forum ARCHIVE: Horizontal scratches on film

This is topic Horizontal scratches on film in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

To visit this topic, use this URL:
https://ft-forum.com/ft/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=1;t=006699

Posted by Dan Kegley (Member # 1611) on 11-07-2004, 10:24 PM:

Help... I can't figure out what is causing horizontal scratches on the film? They are not in the same place and they start at the bottom and work there way up. Some frames have one scratch and others have three and others have two and never in the same spot. What do I do to stop this? It happened about a month ago to a print and now again last night. [Confused]

Posted by Randy Stankey (Member # 64) on 11-07-2004, 11:04 PM:

Are they kind of diagonal? Mostly sideways but at an angle? Do you feel like you're watching the movie through a chain link fence?

The first thing I would suspect is a mis-thread at the point where the film returns to the rewind/takeup platter. See if the film is/was dragging along the edge of the platter.

What kind of platters do you have? Christie? SPECO? Strong?
That information would be VERY helpful.

Posted by Mark J. Marshall (Member # 1409) on 11-07-2004, 11:30 PM:

Hi, Dan. Welcome aboard!

I'm with Randy. Without knowing anything else, the platter deck is the most likely culprit. There are lots of threads on identifying the source of scratches here. Click the search button, and enter 'horizontal scratches'. You should see all kinds of stuff that may help you out. If you're still stuck, give us some more details... platter model, projector model, scratch color, does it occur all the way through the print, only at the beginning, only at the end, etc. Any info would be helpful.

Cheers!

Posted by Monte L Fullmer (Member # 2797) on 11-07-2004, 11:57 PM:

I've ran into this as to where guidance rollers between transport assembly and projector is the main culprit for horizontal scratching. Film stressing across the rollers can leaves a good "footprint" going across the emulsion, or even the base side of the film. Guidance rollers that are not in square with the film path are prone for this sort of scratching. I've usually maintained that the upper and lower rollers of the projector are square and even with the upper and lower rollers of the platter. Rollers that are at an obtrusive angle coming from the machine (where the film is almost travelling in a horizontal position),esp where the film is leaving the failsafes is being under extreme stress at that point until it heads into a more up/down film path back to the platter-the way film likes to run. I've seen so many pictures in the "picture warehouse" of film paths so obtrusuve is that I wonder if those prints are getting scratched with all of the bending and twisting that the film is being placed under. Too bad we can't all go back to reel to reel changeover booths where film was handled much more simpler and easier - perfect vertical film feed. THX, and good luck.

Posted by Randy Stankey (Member # 64) on 11-08-2004, 12:27 AM:

quote: Monte L Fullmer

Rollers that are at an obtrusive angle coming from the machine...

quote: Monte L Fullmer

I've seen so many pictures in the "picture warehouse" of film paths so obtrusuve is that I wonder if those prints are getting scratched with all of the bending and twisting that the film is being placed under.

I DO agree that it would be wise to go through your film path to make sure the film isn't misaligned with a roller or dragging across some place it shouldn't

I DON'T agree that film rollers should always be at 90º angles all the time. If the film isn't coming in at a perfect 90º in the first place then it's not logical that it should be forced to run that way. Further, if the film makes a "compound bend", as it often does at the Upper Magazine Roller the film must NOT be forced to make a right angle turn.

If you know carpentry, you understand that in order to make a "compound miter joint" you have to use two complimentary angles to make a 90º corner in the two pieces of wood. In routing the film, a similar theory applies.

Do you want to see an "obtrusive" film path?!

Go to THIS PAGE!

You'll probably shit yourself! [Big Grin]

I guarantee that not one millimeter of film got scratched on that day! (Or ever, for that matter!)

The secret is to check and double check your rollers to make sure the film rolls over them smoothly without touching anything they shouldn't be. Get some scrap film and use it to test things out while you make your adjustments.

Posted by Dave Ganoe (Member # 53) on 11-09-2004, 02:08 PM:

We use christie platters where I work and have had the same problem. It is caused by the film riding on the side of the roller of the swing arm below the platter deck.

Posted by Brad Miller (Member # 2) on 11-09-2004, 02:58 PM:

From the guy's description, it sounds to me like a loop scratch from an oversized loop, very common especially with older Christie projectors that do not have the slap guards, but can happen with most machines.

I have never, ever seen the AW3 takeup arm be capable of creating a scratch. That would require a serious misthread with the roller cocked to achieve that.

Posted by Will Kutler (Member # 770) on 11-09-2004, 04:09 PM:

Do you clean your sprockets/film-path with a tooth brush? Also sounds like a brush bristle or something might be cought on the intermittent sprocket.

Cheers

K.

Posted by Ramin Hashemi (Member # 2694) on 11-11-2004, 07:55 PM:

Follow the film from Feeding platter, and just before it goes down in the projection, there is a place that the film can rub against the frame of the projector if it is not fed in front of the roller. That would cause the film to touch a horizontal frame of the projector, and cause horizontal scratches.

Posted by Gordon McLeod (Member # 33) on 11-12-2004, 09:31 AM:

If it rubs against the frame of the machineyou will have verticle scratchs