Film-Tech Forum ARCHIVE: Scratches on Print

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Posted by Ian Bailey (Member # 1752) on 03-16-2004, 08:55 PM:

I have had a few problems recently with prints showing scratches on them.One print has a fine continuous black line down the middle of the image and the other had short(yellow-green)scratches on the right hand side of the projected image.These short scratches were at a 45degree angle and appeared at a regular interval.We filmguard every print when we make it up,the only thing I can find is gritty dirt on the soundhead ruber layback roller.Would the use of filmguard cause dirt to be attracted to the rubber layback roller?
Our equipment is Simplex 35(1050) projector/Simplex soundhead/Speco Platter.
What is the difference between a black scratch and a yellow green scratch?
What can be used to clean the rubber layback roller on the sound drum?

Posted by Daryl C. W. O'Shea (Member # 1303) on 03-16-2004, 09:06 PM:

The yellow-green diagonal scratch was probably caused by either something caught on a sprocket (brush hair, etc) or by the film being scratched by the platter while building the print.

Coloured scratches are on the emulsion side, that's the side towards the lamphouse, or the side facing you with the film heads up and sound track on the left.

Black scratches are on the base side of the film. That'd be the side facing the screen, or the side facing you with the film heads up sound track on the right.

You could probably clean the rubber with a cloth if it's got a residue of FilmGuard built up on it. If it's got crap embedded in the rubber you can try picking it out. If it's really bad you might consider replacing it.

Posted by Peter Mork (Member # 1336) on 03-16-2004, 11:52 PM:

The sort of question that's hard to answer at a distance.
Another likely culprit for those diagonal scratches is a roller going to or from the platter. If a flange drags over the emulsion side, bingo. You can sometimes tell by noting the distance between scratches what diameter the roller was that did the deed, and that can narrow down the possibilities.

Any roller that swings freely on a bracket, notably the last one that feeds the film onto the platter, is especially suspect. I'm a strong advocate of gluing a disc of felt to the outside of any roller flange that MIGHT be a problem, and trimming it so it extends just a tiny bit over the flange edge. Yes, you're supposed check your lacing each run, but with thousands of runs accidents do happen, and the felt is your insurance that a mis-threaded roller won't damage the print.

Posted by William Hooper (Member # 71) on 03-17-2004, 12:17 AM:

quote:
The yellow-green diagonal scratch was probably caused by either something caught on a sprocket (brush hair, etc) or by the film being scratched by the platter while building the print.

The diagonal scratches are 99% likely to be caused by making up to the platter. This runs the risk of another platter/changeover war of proselytization, but the fact is that the world knows those diagonal scratches by the name "platter scratches".

Just to get the first 20 posts out of the way:
blah blah blah platter scratches blah blah blah cinch marks blah blah blah platter scratches blah blah blah cinch marks blah blah blah

Posted by Michael Schaffer (Member # 1204) on 03-17-2004, 01:22 AM:

blah blah. blah blah, blah "proselytization" (!) - blah blah! blah blah blah blah. blah blah blah blah blah? blah blah...

Posted by Ian Bailey (Member # 1752) on 03-17-2004, 05:08 AM:

Could I have a bit more information on what I should be looking for if the scratches were made by building the print up to the platter.

Posted by Darryl Spicer (Member # 711) on 03-17-2004, 10:02 AM:

Make sure the picture area is not making contact across the surface of the platter deck. However, if you are loading the film onto the platter with the soundtrack up contact on the platter surface would have been the base side of the film not the emulsion side. I noticed that you use the Speco platter. Are you using the newer style gray makeup table or the old wooden tables. If you are using 60 min reels make sure they are in good condition and not warped causing the picture surface to come into contact with the flangs during build-up.

Posted by Daryl C. W. O'Shea (Member # 1303) on 03-17-2004, 02:44 PM:

Unless of course he's got the film twisted the wrong way and low enough that it doesn't try to stand on edge, then it'd be the emulsion side.

Does the diagonal line(s) repeat in the same spot every frame, or are there just lots of diagonal lines, continuously?

Posted by Patrick de Groot (Member # 858) on 03-17-2004, 02:57 PM:

quote:

Coloured scratches are on the emulsion side, that's the side towards the lens, or the side facing you with the film heads up and sound track on the left.

Is it not that the side opposite to the screen/lens is the emulsion side?

Posted by Daryl C. W. O'Shea (Member # 1303) on 03-17-2004, 03:03 PM:

You are correct. For some reason I thought the lens was in the lamphouse last night. Probably because I had just watched a science documentary where they had the lens in the lamphouse. At least I got everything else right... including base towards the screen.

Post corrected to avoid confusion.

Posted by Ian Bailey (Member # 1752) on 03-17-2004, 09:08 PM:

We are using the newer style make-up table and we adjust the top roller on the MUT so the print rides onto the platter on the non-soundtrack side edge of the print.The picture area does not come in contact with the platter surface.The diagonal lines would be more than a frame apart and they appear and disappear at a constant rate,one will appear at the top of the screen and the next will be a bit lower down etc.I'd say the marks are on every second or third frame,as if it had come from a roller the size used on a platter.We have checked everything several times and the only thing we found was a small rough edge on the rubber layback roller on the sound drum.I will double check the next time we make-up a print on this gear and make sure we are not doing anything that you guys have suggested that could be causing the problem.I appreciate your comments.

Posted by Daryl C. W. O'Shea (Member # 1303) on 03-17-2004, 10:16 PM:

Sounds like somebody missed a roller. Probably the roller on the lower arm of the projector. If not that one, the lower takeup roller on the platter.

Posted by William Hooper (Member # 71) on 03-18-2004, 01:48 AM:

You literally have to find it like finding a piece in a jigsaw puzzle. The 'missing piece' is that spot on the film where it's scratched. Identify which side the scratch is on, makeup or thread up as usual, & look along the path of the film for where it is contacted on that side at that spot.

Posted by Demetris Thoupis (Member # 833) on 03-18-2004, 03:13 AM:

The first thing you should do is check the roller path from the platter to the projector and then back again. The film has to be passing through the rollers exactly in the middle. Try cleaning the rollers first and make sure they are turning. If the rollers are not turning then the film might be scratched on them and that might be the result of your black line. Also check the gate of the projector. Is there any dirt? The best thing is to dissasemble it, clean it well and then put it back in. Some might dissagree but put WD40 on the base of every roller that is not turning. Make sure that your gate is not too tight as well. Also check the levelling of the platter. If it is bend and the film rubs hard on it while it returns on the platter then you have a problem.
Hope this could help.
Demetris

[ 03-18-2004, 06:36 AM: Message edited by: Demetris Thoupis ]

Posted by John Pytlak (Member # 331) on 03-18-2004, 05:42 AM:

For 35mm prints, the film's emulsion side faces the lamphouse.

A camera negative is exposed with the emulsion toward the camera lens. A direct print flips this orientation, so the emulsion then faces AWAY from the lens. And the normal master positive to duplicate negative duplication system maintains this orientation.

The image in the gate should be upside-down, with the analog soundtrack on the outboard side of the projector.

16mm reversal camera originals (e.g., EKTACHROME or KODACHROME type films) have the emulsion facing the projector lens. 16mm prints can have either orientation.