8mm Forum: Determining polyester or acetate stock

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Topic: Determining polyester or acetate stock

Jim Hepler
Junior
Posts: 4
From: St. Louis, MO, USA
Registered: Feb 2013

posted February 27, 2013 08:05 PM

I was just wondering if there's a quick way to determine if a super 8 print is on acetate or polyester? I just got the 800' Universal 8 version of Slap Shot, and it has a chemically, possibly vinegary smell. But, it also has a sticker saying it was cleaned, so I thought maybe it'd been chemically cleaned. If this was a polyester print, I figure I'd know for certain it was not vinegar, and just cleaning agents I'm smelling.

Any thoughts guys? Thanks!

Also, this is my first post! Hi everyone! I do intend to post more, as I'm just getting into film collecting. It's an addicting hobby already. [Big Grin]

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Adrian Winchester
Film God

Posts: 2941
From: Croydon, London, UK
Registered: Aug 2004

posted February 27, 2013 08:32 PM

Welcome to the Forum. I have never heard of a polyester Universal 8 print. But apart from it being a bit thinner, you can easily check by tearing off a frame or two from the start or end - if it breaks easily, it's acetate. I have never heard of a U8 release with VS - I think the smell is probably the cleaning but I can't be certain.

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Adrian Winchester

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Jake Mayes
Expert Film Handler

Posts: 119
From: Bath, UK
Registered: Sep 2012

posted February 27, 2013 08:47 PM

Try tearing a tiny piece, if you find it difficult or it stretches, it is polyester. or place it between two polarisers: http://www.paulivester.com/films/filmstock/guide.htm

That will give you an example. For audiotape i found holding it up to light while wound on a spool tightly was a good indicator as well, acetate was partially transparent, while polyester appeared opaque.

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Jim Hepler
Junior
Posts: 4
From: St. Louis, MO, USA
Registered: Feb 2013

posted February 27, 2013 09:25 PM

I was able to tear off a piece - felt more like breaking it off than tearing it actually. It's also translucent under light on the reel.

I might add the faintly vinegary smell seems to have faded significantly already - it was in a hard plastic bottom opening container, and leaving that open seems to have helped. I'm still suspicious though - if it has VS, is it safe for my other films if I project it?

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Joe Balitzki
Jedi Master Film Handler

Posts: 529
From: Charleston, SC, USA
Registered: Aug 2005

posted February 27, 2013 09:27 PM

I believe I have a 800' U8 Digest on Polyester Stock. But it was a late printing near the end of U8. I do have a U8 Cartoon on Polyester Print Stock. The easiest and fastest way to tell is the tear test as described above.

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Movie Lovers Do It in the Dark

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Adrian Winchester
Film God

Posts: 2941
From: Croydon, London, UK
Registered: Aug 2004

posted February 27, 2013 10:05 PM

Projecting it if it had VS would not put your other films at risk. You can buy 'A-D Strips' to test for VS but it would be a lot of money to buy a pack if you're only worried about one film.

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Adrian Winchester

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Matt McBride
Film Handler

Posts: 62
From: Starkville, MS USA
Registered: Oct 2012

posted February 27, 2013 10:37 PM

The tear test works good. If you hold the reel up to the light, holding it as if it were a disk, then if you see the light shine through, you got yourself a polyester print. If no light shines through, you have yourself an acetate print.

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Jake Mayes
Expert Film Handler

Posts: 119
From: Bath, UK
Registered: Sep 2012

posted February 28, 2013 08:26 AM

I found the reverse was true in that case... but i only did that rest with reel to reel tape

I had ones smell of vinegar that faded after being removed from the container, remember if they have been in there for years, any offgassed acetic acid will dissipate if it is not too bad, as moisture breaks the acetyl groups away from the cellulose if left for a long time in that state it eventually speeds up the reaction.

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Jim Schrader
Phenomenal Film Handler

Posts: 1628
From: Savage, MN, USA
Registered: Jun 2003

posted February 28, 2013 09:25 AM

Also if you have a Guillotine splicer I have noticed they do not cut poly prints as easy, and if you have a kodak splicer it requires a bit more pressure to cut the film. I've heard vitafilm gives a similar smell to vinegar as well just leave the film in the wide open should slow it down if it has it.

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jim schrader
"Let's see “do I have that title already?"

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Matt McBride
Film Handler

Posts: 62
From: Starkville, MS USA
Registered: Oct 2012

posted February 28, 2013 09:35 AM

Jake, you are absolutely right when it comes to reel to reel audio tape. It will be see through when it is acetate and more opaque when it is polyester. With film it is the exact opposite, fortunately or unfortunately. They gotta keep us on our toes [Big Grin]

I believe, and correct me if I am wrong fellow film lovers, it has to do with the chemical process of the film vs. using magnetics on the audio tape.

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Hugh Thompson Scott
Film God

Posts: 3063
From: Gt. Clifton,Cumbria,England
Registered: Jan 2012

posted February 28, 2013 10:56 AM

Jake & Matt are quite correct in that if you hold it up to the light
you can see your fingers through it, then it's polyestar. Try to break it at the sprockets, it won't only twisting & creasing, it's
polyestar.

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Winbert Hutahaean
Film God

Posts: 5468
From: Nouméa, New Caledonia
Registered: Jun 2003

posted February 28, 2013 01:11 PM

quote:
I have never heard of a polyester Universal 8 print.

Adrian, I have seen many U8 two parter spooled onto 600'. So This must be polyester.

I have also some U8 that is seen not full on a 400' reel but the length is just enoguh for 17 minutes. So this must be polyester too.

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Winbert

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Osi Osgood
Film God

Posts: 10204
From: Mountian Home, ID.
Registered: Jul 2005

posted February 28, 2013 01:51 PM

Acetate, (even brand new acetate prints) tend to have a yellowish cast to the color, which is entirely frustrating because it does affect the overall color scheme just a little.

The film lab still using this stock does it's best to compensate for that in they're color timing, but sometimes, it's just too painfully obvious.

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"All these moments will be lost in time, just like ... tears, in the rain. "

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Jim Schrader
Phenomenal Film Handler

Posts: 1628
From: Savage, MN, USA
Registered: Jun 2003

posted March 01, 2013 12:12 PM

here is a picture of both the film on the red reel is poly stock and the one on the left is acetate. while the acetate is still see through it is not as clear.

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jim schrader
"Let's see “do I have that title already?"

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