Emulsion build-up on Simplex tension bands

[Jesse Crooks]

At a theater where I regularly fill in as a projectionist, I have started to find heavy emulsion build-up on the tension bands on one of the two projectors. I usually have to deep clean the projectors if its been a while since my last visit, and they run a lot of "grindhouse" prints, so the first couple times I just assumed it was a result of the prints they were running and a lack of cleaning. However, I think this is the third time I have now come in to find heavily caked emulsion in the same locations on the bands (worse on the outboard band, heaviest near the lateral guide disc on the outboard band, and towards the bottom of the inboard band), and only on Projector 2. It's bad enough that it's difficult to scrape off. They must have run a black and white film most recently, because it's usually purple, and thus clearly shed emulsion. To the naked eye there doesn't seem to be anything wrong with the gate (curved runners look nice and smooth), so I'm confused as to what may be the source of the problem.

It's probably unrelated, but last year I replaced the tension bands on Projector 1 because they had done something (I can't even imagine what) that punctured a hole in and cut a nick in the outboard the tension band. I tried to figure out how on earth that happened and couldn't come up with a plausible scenario. I'm wondering if whatever was done to cause that damage may have also been done to a lesser degree on the other projector. At that time we sourced two pairs of tension bands but I only replaced the obviously damaged ones in order to get all the life we could out of the "good" set in the other projector. I could replace these as well, but I have no idea whether the likely source of the issue is just wear on the tension bands, or if it may be caused by something else (ex., a gate issue) in which case the new bands might also be damaged if the underlying problem isn't resolved. I don't want to waste NOS tension bands if they'll also get damaged.

Or maybe I'm just overthinking it, and if they cleaned the damn projector after every reel there wouldn't be any buildup. My primary concern is that this is resulting in film damage.

[Ryan Gallagher]

We check/clean (with isopropyl) ours before and after every print run. If there is any pitting, even fairly well hidden to the eye, it will have a tendency to build up dust from old prints, which depending on how abrasive the dust is, will then start damaging the emulsion too. Which is why it's important to get a clean slate before each print. An archival house might even clean them between each reel change!

Since you have a pair of NOS bands, I would say swap them and see if the problem problem is reduced. But old dirty prints are frequently gonna deposit something each run.

The stubborn stuff can be scraped off with a plastic spudger. Old timers swear by an actual copper penny. I find that Film-Guard does a better job at loosening up deposits than alcohol.

I don't have Simplexes here, but I imagine what gate tension they are having to run them at can also have an impact.

[Jesse Crooks]

I would consider cleaning the gate and trap between every reel change to be the absolutely bare minimum, even if you're rushed. I try not to actually pull the trap out during a show unless it gets really bad (and usually only during a marathon when other prints are coming up when I don't want to transfer the dirt from a nasty print to a good one), but I brush it out and clean the tension bands with 99.9% alcohol after every reel. I wouldn't use a penny on the tension bands. Even if it's a softer metal, it's a thin, unsupported strip. I only use a fingernail and put my thumb underneath the band to support it when scraping. Increasing the tension just while cleaning also helps stabilize the bands to make it easer to scrape the emulsion off.

I don't want to waste a consumable part that I will need in the future. These ones we had to source from one of the other projectionist's friends. That's the way it will be for all parts moving forward. You need to hoard what you can because who knows how hard it will be to find a replacement.

The tension is always set to 1, as it should be on a Simplex. I have never come in to see it set to anything else.

[Brad Miller]

As Ryan noted, a cheap toothbrush (not the "soft bristle" type) with a tiny spritz of FilmGuard onto the toothbrush will definitely do better than alcohol. If you are worried about the slow-evaporation of the FilmGuard, just take a shop rag and give the bands a simple wipe after you give them a quick scrub with the toothbrush. (That toothbrush with FilmGuard also works quite well to get any dirt off of the sprockets, just don't ever do it with the machine running.)

I definitely agree with Jesse not to use a penny (or a flathead screwdriver or a razor blade or any of the other various things people use that causes damage) on the bands. If the bands are not abused, they should never need to be changed. The more film ran on them, the better they become.

[Randy Stankey]

Years ago, when I took the test in order to get my Pennsylvania projectionist's license, there was a question:

What is the BEST way to remove dirt and buildup from the film trap?

A) Gasoline or kerosene.
B) Sandpaper or razor blade.
C) Soap and hot water with a toothbrush.

Of course, none of those answers are reasonable but the "best" answer on the test is Option-C. (Soap and water.)
After the test was over, a bunch of guys were standing around, outside, smoking cigarettes and laughing about the questions on the test.

[John Eickhof]

I used to keep a bottle of XeKote or Film Guard on hand to clean the traps...I ran straight gate XLs and set up for dailies so I had a set of traps with bamboo runners ( still have them) that were used with fresh struck unwaxed dailes if the film was really green you had to apply a little to the edge as the film entered the gate to keep from sticking...the later delrin runners Howard Straight made were much better and didn't get as noisy as the bamboo ones.

[Paul H. Rayton]

I occasionally had wax buildup from certain prints on the metal pressure bands in the gate of my Norelco/Philips DP70s. A simple swab with a water-moistened tissue or soft wiping cloth (cotton, for example) will dissolve the wax quite readily. So, in the absence of any of the chemicals mentioned above, just get a little jar of plain ol' water and give it a try.
There is also a school of thought on those Norelco/Philips bands that has them covered with narrow strips of felt. In that case, there were never any deposits. It would help to dust off the felt strips now and then, but they never accumulated any solid masses of wax or other material. Kinoton used to sell the narrow felt strips for those bands, but I'm not sure if there is anyone presently providing a supply.

[Mark Gulbrandsen]

Jessie, My experience with XL's, and Century's is about the same as what you show in the image. Seems like the larger the lamp used, the more gunk build up there is. Also, not all films are waxed the same, and there is emulsion out to the edges as well...

When Wolk was still in business, we had him make us DP-70 bands as the parts from the then supplier had become ludicrous. Not sure the exact metal he used to make them out of, but his bands did not have hardly any build up issue. He also made for us Compound Curved gate runners. Not only did this greatly improve the overall focus of the DP-70 when running larger lamps, but they also built up almost no residue. The improvement in focus was very evident when running the heat absorbent Schneider test film. I never could understand why Phillips placed that little flat spot at the aperture on the gate runners. Also note that all the DP-70's that we rebuilt and installed back then, did first run duty.

[Mark Gulbrandsen]

I used to keep a bottle of XeKote or Film Guard on hand to clean the traps...I ran straight gate XLs and set up for dailies so I had a set of traps with bamboo runners ( still have them) that were used with fresh struck unwaxed dailes if the film was really green you had to apply a little to the edge as the film entered the gate to keep from sticking...the later delrin runners Howard Straight made were much better and didn't get as noisy as the bamboo ones.

John,
Bamboo? That's hilarious! I did dailies on 45 shows with Straight Gate C's with no special gates, and there was zero film damage or wear, I ran about half those shows myself... Uncle Buck alone was 1.5 million feet, and the first rough cut was 4 hours and 10 min long. Since I had three sets of dailies systems, I often used other operators, or a person from Editorial. This obviously involved literally millions of feet of freshly processed film, and they went through straight gate C's perfectly. I sold three sets of the exact same dailies projectors to a camera operator in Florida, and two more sets to post houses. No one ever requested special gate gunners made of unobtanium, or mahogany, or plastic. So what was with the X-L's that caused the standard straight gate to be so finicky with freshly processed film?

Left Photo: Prototype system on Home Alone
Right Photo: Finished system on Free Willy 2 - Customers System

[Steve Guttag]

... I never could understand why Phillips placed that little flat spot at the aperture on the gate runners. Also note that all the DP-70's that we rebuilt and installed back then, did first run duty.

Oh...I think I know the answer to that one! I'm battling a pair of FP75E where they have a notable curve to them...but no flattened part around the aperture. My theory is that the longer EF lenses (140mm and up) can't deal with that much variation in the depth of focus. Side-to-side focus is fine and uniform across the screen...top to bottom, not so much. You can have top and bottom in focus or the center, never both. I'm looking to get some skates/runners made that goes back to a DP70esq tri-radius design. I want the radius in the aperture area to be very long though not quite flat.

For 35mm, this is less of an issue as the aperture is 1-perf shorter (and even more so on most formats) as well as the EF of the lenses getting notably shorter, which can deal with the curved field better.

Interestingly, for the DP75, in the aperture area, they went to completely flat. Above the aperture it is a reverse curve and below the aperture a decent curve to hit the intermittent.

As for Jesse and the build-up. I would, at least, try the new bands and see if it addresses the problem. If it doesn't you can always go back. If it does, then you should keep them on as you are clearly removing material from the prints and seek out new bands (or possibly good-used...there are a ton of Simplexes sitting in AMC theatres around the country).

[Ryan Gallagher]

Oh...I think I know the answer to that one! I'm battling a pair of FP75E where they have a notable curve to them...but no flattened part around the aperture. My theory is that the longer EF lenses (140mm and up) can't deal with that much variation in the depth of focus. Side-to-side focus is fine and uniform across the screen...top to bottom, not so much. You can have top and bottom in focus or the center, never both. I'm looking to get some skates/runners made that goes back to a DP70esq tri-radius design. I want the radius in the aperture area to be very long though not quite flat.

For 35mm, this is less of an issue as the aperture is 1-perf shorter (and even more so on most formats) as well as the EF of the lenses getting notably shorter, which can deal with the curved field better.

Interestingly, for the DP75, in the aperture area, they went to completely flat. Above the aperture it is a reverse curve and below the aperture a decent curve to hit the intermittent.

As for Jesse and the build-up. I would, at least, try the new bands and see if it addresses the problem. If it doesn't you can always go back. If it does, then you should keep them on as you are clearly removing material from the prints and seek out new bands (or possibly good-used...there are a ton of Simplexes sitting in AMC theatres around the country).

I would have thought the field focus issue would be exaggerated at shorter focal lengths (wide angle)? Our 5perf lenses are 175mm, and we do not struggle with focus too much other than as expected due steep booth angle. The curved gate does not fight us too much on the focus topic, with JJs curve.

[Mark Gulbrandsen]

Steve,
DP-70's never had a tri-curve that I'm aware of, and all the manuals and brochures show the one with the flat area at the aperture. Jim Bond in Chicago had Charlie make the compound curved runners first, and I saw the huge improvement on his pair. At Claco we first had Wolk make gate bands, and a year or so later we had him make the runners. We sent him a new original factory runner, and one I had gotten from Jim. Wolk apparently had never made drawings, but found he had some of it stored in his CNC mill. So everything was measured again to make more. Charlie also stated that he wondered why they ever put a flat spot in the aperture area to begin with. Anyway, the compound curved runners they made solved. focus issues and slightly increased the LPMM rez. I've never seen the gate on a DP-75, but you can bet they are made of Delrin like the FP-20 and other later phillips runners are. A mold to make more would be prohibitively expensive. As would machining them from a solid block of Delrin.
Back to the flat spot, perhaps it being there had to do with theaters originally using powerful Arc lamps... That is the only "mabie" reason I've ever come up with .. Somewhere I have a picture of both runners side by side. I'll have to look for it.

[John Eickhof]

Mark, I think the bamboo rails were thought of or at least machined by Howard at the behest of a person or persons at the studios, according to Jim Gillespie, they had made bamboo runners for the E7s before updating to the XLs in the 1950s, plus the studios at that time seemed to prefer the 3 shoe straight gate plus, the curved gate wasn't introduced on the XL until several years later into production. right up to the end the 3 shoe trap was in production listed as 'studio type' and the long 2 shoe was the standard flat trap. All the studios I ever did service work in and many screening rooms never used curved traps.

[Steve Guttag]

Mark, the DP75 uses metal just for the straight section around the aperture. Delrin is used above and below. However, below the aperture, after the film leaves the metal skates, there is nothing pushing/holding the film in the guide/trap area other than the intermittent sprocket.

I'm reasonably certain that the DP70 runners had the three radiuses but I don't have a runner handy to verify. A lot of the DP70 skites I dealt with had grooves worn in by the mag tracks. There is a TSI about sanding down the runner to get a fresh surface and, of course, keeping the thickness uniform/symmetrical. They don't list the radius just that the height measure above the aperture has to be the same as the height below the aperture.

The FP75E skates/runners are ALL delrin and are, indeed, cut from a block of delrin and machined.

Yes, the JJ runners are just the one radius, Ryan and they are, relatively shallow (long radius). One is more apt to get focus uniformity issues on a JJ from the lens mount not being square to the gate (what Barco people would refer to as Scheimpflug). Back in the day, if you had a long/heavy lens, there was a front lens support to help support such heavy lenses and part of the adjustment was to get a uniform top-to-bottom focus. We had that at the Uptown in DC as our 70mm format lenses were 62mm. 175mm lenses for 70mm format? Pray tell, who made them? Schneider and ISCO stopped at 150mm for their 70mm format lenses, on the late model ones. I tried some Kiptars in that range and they would vignette.

As for depth of field/focus and EF. If you have some lenses handy for an SLR...look at the f-stop ring and note how close focus ranges are on longer lenses versus shorter ones (EFs). Teles have much shallower depth of fields. In fact, one of the issues with filming in 65mm is that you have almost no depth of field. It completely changes how you film a shot to get the look you want. That and 65mm needs a lot more light (bigger aperture to light up and you are going to want to stop down the lens to get your depth of field back).

[Mark Gulbrandsen]

Interesting John! There must have been some sort of print stock that remained sticky for quite a while after processing. Perhaps Ansco or Agfa stuff back in the day... Just not a thing I ever ran into, even with stock that was just a few hours out of the processor. They also never used any Estar stock for dailies except for 8 perf SFX shots and prints of such, Was consistently acetate stuff.