8mm Forum: Determining polyester or acetate stock

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Posted by Jim Hepler (Member # 3550) on 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]

Posted by Adrian Winchester (Member # 248) on 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.

Posted by Jake Mayes (Member # 3292) on 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.

Posted by Jim Hepler (Member # 3550) on 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?

Posted by Joe Balitzki (Member # 438) on 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.

Posted by Adrian Winchester (Member # 248) on 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.

Posted by Matt McBride (Member # 3311) on 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.

Posted by Jake Mayes (Member # 3292) on 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.

Posted by Jim Schrader (Member # 9) on 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.

Posted by Matt McBride (Member # 3311) on 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.

Posted by Hugh Thompson Scott (Member # 2922) on 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.

Posted by Winbert Hutahaean (Member # 58) on 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.

Posted by Osi Osgood (Member # 424) on 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.

Posted by Jim Schrader (Member # 9) on 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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