Your thoughts on this : POLYESTER IN DETONATION

[Frank Raia]

What are you guys thoughts on this : POLYESTER IN DETONATION: THE MYTH OF IMMORTALITY BEGINS TO CRACK



https://mimundoensuper-8.blogspot.co...tvshd_bYMkUrwg

[Brad Miller]

I didn't have to read the entire article. This is not some sort of groundbreaking discovery. It's just blocking and it has been well documented. The author just doesn't have much actual film knowledge.

Polyester is NOT "forever". It is NOT immune to all kinds of degradation. I've actually seen more polyester prints suffering dye and blocking issues than acetate prints turning VS, plus polyester scratches easier than acetate as well.

It's pretty simple, do NOT wind polyester film super tight for storage and keep the humidity low. High humidity and/or tight winding will cause blocking and dye issues on polyester base prints.

[Ryan Gallagher]

I didn't have to read the entire article. This is not some sort of groundbreaking discovery. It's just blocking and it has been well documented. The author just doesn't have much actual film knowledge.

Polyester is NOT "forever". It is NOT immune to all kinds of degradation. I've actually seen more polyester prints suffering dye and blocking issues than acetate prints turning VS, plus polyester scratches easier than acetate as well.

It's pretty simple, do NOT wind polyester film super tight for storage and keep the humidity low. High humidity and/or tight winding will cause blocking and dye issues on polyester base prints.

How tight are we talking? Is there kinda a catch-22 now?... as a decently tight wind is in theory safer for shipping, but at least with back catalog release prints, many sources are not inspecting and re-winding them for storage... they just go directly on a shelf and back out to the next person.

It would be different if every film was handled upon return and things like storage wind tension addressed... but those days appear to be behind us now.

[Frank Raia]

Very interesting Brad. Does film guard help with longevity?

[Randy Stankey]

I once worked in a plant that makes plastic bottles, similar to plastic Coke bottles. I learned a few interesting things, there.

The polyester that film is made from is almost the same stuff that plastic bottles are made from. There are a few different additives but the main material is the same.

One thing that surprised me to learn is that polyester is hygroscopic. It absorbs water. In fact, the manufacturing plant had to be climate controlled...humidity and temperature...or else the bottles wouldn't come out right. The stuff is also slightly gas-permeable. So, yes, the fizz will gradually diffuse out of that bottle of Coke you just bought. It will take a long time for the fizz to completely go away. It would probably take years or decades, certainly long enough for the product inside the bottle to go bad before a noticeable amount of fizz leaked out. Neither is it completely inert. Polyester will react with acids, UV light and other things that, over time, will degrade it.

I didn't, specifically, know about film fracturing but I have seen similar problems. In the bottle plant, preforms are heated and blown into molds with about fifty atmospheres of air pressure. Sometimes, because of a flaw in the preform, bottles can fracture when they are being blown. It sounds like a shotgun going off! It brings the whole machine, the size of a school bus, to a grinding halt!

It usually takes a long time for polyester to degrade so I can understand why many people think that polyester is some kind of wonder material. It may be good but it's not "that good."

[Leo Enticknap]

The important takeaway for me is that it appears that not all polyester is made equal: the quality of manufacturing and processing appears to affect its longevity in storage. It's the same syndrome whereby nitrate manufactured from around 1895-1915 is, paradoxically, more likely to survive than stuff made in the 1940s, when the combination of wartime austerity and huge demands for release prints forced the use of cheaper wood pulps that required a higher concentration of nitric acid to dissolve to form the cellulose base.

Agreed completely with the article's author that many mass production release prints made during the final decade of 35mm as a mass medium were of shockingly variable quality, with some being extremely poor.

[Ryan Gallagher]

I've definitely seen blocking or crystalizing effects on a couple trailers I gambled on via ebay... I assumed due to poor storage or humidity levels, or being subjected to floods, but wind tightness could have aggravated it I suppose. One or two felt like trying to peel tape off a roll, the wrap was so adhered to the wrap below it, particularly at the SRD track area. Essentially junk.

[Frank Raia]

So what is everyones storage techniques? We know low humidity, cool temps. Now I found out not to wind to tight, still not sure what is too tight. Some put in vented cans. What else?

[Jesse Crooks]

I have almost exclusively seen this on trailers with a rock hard wind that have never been rewound from their 1" cores. Probably tighter than you'd get with a typical tight winder. They were like hockey pucks when you received them from the distributor.

[Jesse Crooks]

BUT just today one of my projectionists found what I believe to be blocking at very end of a reel they were inspecting. The torn section was stuck to the layer below it and it had to be pried apart. He called for advice so I didn't see it in person, but it certainly seemed like blocking from the FaceTime video.

[Jesse Crooks]

For what it's worth, the recommended "preservation wind" for acetate is below 300g of holdback tension, or 2.9N. That's pretty much smack dab in the middle of the SMPTE recommended tension for 35mm, which is 1.7 to 4.4N.

[Frank Raia]

Jesse, that looks horrible. That was poly? So how do you measure tension on the mut?

[Ryan Gallagher]

Jesse, that looks horrible. That was poly? So how do you measure tension on the mut?

For MUT tables I have no practical experience. Are they sync'd to platter motors or is the MUT literally pulling film and causing the platter to spin?

But for any winder or reel arm with a slip clutch (or non-active slipping motor), tension can be measured with a simple spring guage and a section of film with a foldback to make an eye for a bent wire or string loop to allow the guage to hook on. You simply pull film off the reel/core using the spring guage, or in the case of takeup arms, allow the spring guage to completely counteract the slip clutch and it holds the reel still.

Note you might have to reinforce that fold back, I used some gaff tape, as some tensions will just split the film at the crease. The tension of course varies as the diameter of the film grows, unless you have a fancy way to promote uniform tension over the course of the wind as Brad has discussed in other threads. I take an empty and full measurement for my target reel/core sizes when adjusting.

I picked up this set of gauges, depending on which device i'm measuring in the booth, several of the different ranges are useful. My only gripe is that the black on clear text is very hard to read without an extra light at just the right angle.
https://www.amazon.com/dp/B08GM1SP1C...n_title_1&th=1

[Jesse Crooks]

Yes, that's polyester. We do reel to reel, so no MUT. When I'm calibrating clutch holdback tension I use a spring scale. I take a piece of leader, fold over the end and tape it down to form a loop, then add a piece of string to the loop in order to hook the spring scale to it. I wrap it around an empty reel to test the maximum and a full reel to test the minimum. Pull the scale and check the measurement when the reel begins to move. It's not super precise (good luck pulling it perfectly evenly) but it's good enough.

[Jesse Crooks]

I usually calibrate them using standard 2k house reels with 5" hubs. In that case, I won't rewind anything smaller than a 3" core on that table. I'll transfer anything on a 1" or 2" core to something larger with hand rewinds because the tension is way too high by the time you get to the end of the reel. At home I usually work with 3" cores, so I use 3" cores on split reels to calibrate it. For my one booth that has a single projector and still runs 6K reels, the projector and rewind table clutches are calibrated for 6k and I use hand rewinds for any 2k reels.