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Topic: PTR Rollers and Nitrate film

Steve Guttag
We forgot the crackers Gromit!!!

Posts: 12814
From: Annapolis, MD
Registered: Dec 1999

posted 07-04-2007 09:46 AM

Have their been any studies on using PTR rollers with nitrate base film? Any known problems of bad interractions or potential damage to the film or the emulsion? Would the Matte (less sticky) version of the roller be preferred or can either be used?

This is probably a John P. type question.

Steve

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John Pytlak
Film God

Posts: 9987
From: Rochester, NY 14650-1922
Registered: Jan 2000

posted 07-04-2007 11:23 AM

Kodak did not specifically test PTR film cleaning with nitrate film, but I know they have been used successfully by film archives on nitrate. The Library of Congress uses film transfer devices built by Jeff Kreines, which uses PTR rollers for both cleaning and transport.

http://palimpsest.stanford.edu/byform/mailing-lists/amia-l/2006/09/msg00024.html

quote:
But what's most important is how the scanner handles film. There are no sprockets -- all the film touches are 3" PTR rollers (8 of them) and the raised edges of the curved teflon-coated gate. Tension can be adjusted so that minimal tension is used on fragile materials, or more tension on VS material that's curly (but the curved gate helps even more).

The prototype machine at the Library of Congress was designed for scanning paper prints, and has restored two Chaplin films (GENTLEMEN OF NERVE and DOUGH AND DYNAMITE), William S. Hart's first film (THE BARGAIN), and has also been used on some nitrate and safety material, including Mary Pickford's lost film LITTLE RED RIDING HOOD, which had, as Frank Wylie put it, the "consistency of a roll of packing tape." It showed last week at AMMI in NY.

When we delivered the prototype machine, someone had donated seven reels of rare WWI footage of the Battle of Liege. It was a nitrate print, in terrible shape. It would break when curved around a sprocket in an optical printer. There was little hope of preserving this film. Since it couldn't take the strain of a sprocket or small roller, the LOC hadn't repaired the perfs (required for printing) because it was likely a lost cause. (And hand repairs of shrunken film take a long time, using an x-acto knife and clear tape.)

So with nothing to lose, we threaded up a roll on the scanner, and hit the button. It scanned without incident, all seven reels. The large diameter PTRs, low tension capability, curved gate, and optical perf sensors all contributed.

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Jim Bedford
Jedi Master Film Handler

Posts: 597
From: Telluride, CO, USA (733 mi. WNW of Rockwall, TX but it seems much, much longer)
Registered: Jun 99

posted 07-04-2007 02:11 PM

John: Love the CAP Code on your pix.

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Steve Guttag
We forgot the crackers Gromit!!!

Posts: 12814
From: Annapolis, MD
Registered: Dec 1999

posted 07-04-2007 02:34 PM

Oddly enough...it is the Library of Congress where I am possibly going to be using them. The films will be projected (so they shouldn't be in a brittle state) and the desire to keep any dirt or powdering from the projection from getting on to the film.

I've noted that the standard rollers can be REAL sticky and they make me nervous until couple hundred feet go by. I've read a paper that claims that cleaning in cool water keeps the excessive stickiness down to a minimum and conversely washing in hot water brings out more stickiness.

So John, if you were in charge...which would you use? Matte or Glossy rollers? Do you have a preference for each type?

Steve

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John Pytlak
Film God

Posts: 9987
From: Rochester, NY 14650-1922
Registered: Jan 2000

posted 07-04-2007 07:35 PM

The matte rollers are slightly less sticky, which slightly decreases cleaning efficiency, but they are less likely to have transport "sticktion" and "plucking" of the soft polyurethane by the film.

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Phil Hill
I love my cootie bug

Posts: 7595
From: Hollywood, CA USA
Registered: Mar 2000

posted 07-04-2007 07:55 PM

Well John, that certainly answers Steve's question with double speak. [Smile]

(I know you'll kill me for this John since you have so much invested in them, but) Having tons of personal experience with 870 and 1570 applications of the PTRs, I cannot recommend them for anything except possibly for film printers...I've had good luck in that application. The use of them on 1570 projectors is ludicrous!

Dunno know about the application for Nitrate. I only know that the hi-speed of 1570 needs the matt rollers and the slower transports can use the "shinny" ones.

In my experience they ALL have proven to be more trouble than they are worth.

Sorry bub! Just my 2-cents from personal experience over the years. [uhoh]

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Steve Guttag
We forgot the crackers Gromit!!!

Posts: 12814
From: Annapolis, MD
Registered: Dec 1999

posted 07-04-2007 08:27 PM

Phil,

Where I use PTR rollers has been VERY effective. That is for archival and EK type prints where the goal is to prevent any cumlative dust/dirt...not for bulk cleaning. I switch them after every reel so there is no significant build up on the roller. One thing I've definately noticed is that the film is CLEANER during the show than during the run through. I normally will use glossy rollers for that first cleaning and matte rollers for subsequent cleanings unless the film was particularly dirty. PTRs only have a limited ability to clean before they fill up and matte rollers has less ability.

Now with Nitrate films...they are by definition archival pieces and irreplacable so my concern is for the film itself. If in doubt, I'm going to use Matte.

Steve

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Phil Hill
I love my cootie bug

Posts: 7595
From: Hollywood, CA USA
Registered: Mar 2000

posted 07-04-2007 08:48 PM

Well Steve, let us know your outcome.

I personally have not had the same luck as you say you've had.

As I mentioned, the only application I found they were good for is cleaning negatives prior to printing.

(I do have several PTRs here for picking up dust-bunnies and lint from my clothes... they work great for that!)

All the other applications are not worth the time involved to clean and restore them.

Again, just my 2-cents from 15 years of personal experience.

Take it or leave it...

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Steve Guttag
We forgot the crackers Gromit!!!

Posts: 12814
From: Annapolis, MD
Registered: Dec 1999

posted 07-04-2007 09:33 PM

I think a difference in my method is that I'm cleaning them after about 2000-feet or less of film...I never let them build up and it is only to keep cumlative dirt off.

Steve

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Gordon McLeod
Film God

Posts: 9532
From: Toronto Ontario Canada
Registered: Jun 99

posted 07-05-2007 10:16 AM

I have always had good luck with PTR on 1570 and found that when we didn't use them the screen dirt was far worse

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Dave Macaulay
Film God

Posts: 2321
From: Toronto, Canada
Registered: Apr 2001

posted 07-05-2007 03:15 PM

For 15/70 they won't clean a dirty print, they just don't hold enough dirt and are "full" after the first reel or two. Cumulatively they do clean up a dirty print quite a bit but it takes a lot of passes. With a new clean print - if the booth is kept clean, and it certainly should be - PTRs will pick up the unavoidable dust that gets picked up and they are a LOT better than using nothing.
The vacuum and rotating brush film cleaner used on early Imax projectors is pretty good but doesn't pick up the really fine dust like a PTR does. I've seen film scratches from these cleaners too when something abrasive gets stuck in a brush, a chunk of grit small enough to stick on the PTR might cause damage but I haven't seen it.

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Paul Mayer
Oh get out of it Melvin, before it pulls you under!

Posts: 3836
From: Albuquerque, NM
Registered: Feb 2000

posted 07-05-2007 03:59 PM

We had great luck with the PTRs at the Caesars Omnimax once we started using them. On a newly-received built-up print (usually covered with wood chips and shipping dirt even if it was wrapped with garbage bags) yes the rollers loaded up very fast. So on these new (to us) prints we had the field flattener cycle every few seconds for the first several shows. That, combined with changing and cleaning the PTRs every show, and changing out the field flattener wiper bars too, had the print cleaned up after a few passes.

Once the print was cleaned up, we'd put the field flattener back to its normal setting (about 20 seconds IIRC) and the PTRs kept the print looking good. We had two sets of rollers, which were changed for every show. The off-show set was cleaned by hand rubbing them under running water then blown dry to be ready for the next show. Visually inspecting the rollers during cleaning let us know how we were doing in regards to keeping the booth clean as well.

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John Hawkinson
Film God

Posts: 2273
From: Cambridge, MA, USA
Registered: Feb 2002

posted 07-05-2007 04:34 PM

One thing I recall seeing are photos of lab equipment with multiple pairs of PTRs in series, rather than just a single pair. I could see that working a lot better.

We have PTRs in our principle 35mm changeover house, and we do find them effective (Sometimes we FilmGuard on the inspection bench if things are really bad, though). We also wash PTRs at the end of each night, which for us is two shows. If print is really dirty, we'll wash PTRs faster. Cleaning them every reel makes a dramatic difference on prints that are abysmally dirty.

--jhawk

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Mark Gulbrandsen
Resident Trollmaster

Posts: 16657
From: Music City
Registered: Jun 99

posted 07-05-2007 06:06 PM

quote: Paul Mayer
We had great luck with the PTRs at the Caesars Omnimax once we started using them.

Paul,

I'm not really sure how you would have been able to tell one way or the other as the screen there was so abysmaly filthy for about the last 5 years that place operated!!

Mark

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Paul Mayer
Oh get out of it Melvin, before it pulls you under!

Posts: 3836
From: Albuquerque, NM
Registered: Feb 2000

posted 07-06-2007 02:01 AM

Easy. The print dirt moved or flashed by. The screen dirt didn't. [Big Grin]

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