8mm Forum: Now, I'm Confused

This is topic Now, I'm Confused in forum 16mm Forum at 8mm Forum.

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Posted by Maurice Leakey (Member # 916) on June 24, 2018, 09:45 AM:

I'm sure everybody will have been reading my 16mm posting about polyester film.

Today I was inspecting a 16mm feature just received, black & white on AG stock. (No date codes on AG stock). Out of its cans and it seemed to be polyester after the suggested test of holding sideways to a light source to see if translucent and even see the outline of your hand through it.

The leader of the second part had presumably suffered from a bad auto-load and had about 9-10 inches of damaged and pulled perforations. Really too much to repair so I cut out the section and re-joined on my CIR.

Before throwing it into my waste bin I tried to tear it apart, not really expecting it to do this as it appeared to be polyester.

To my amazement I was able to snap it very easily in many places.

So was it acetate?

According to many web-sites the test for polyester can be achieved four ways:-

1) The translucent test
2) Not likely to tear
3) Using polarising filters
4) Not able to use cement joins

Now I am most confused. [Embarrassed]

Posted by Jose Artiles (Member # 471) on June 24, 2018, 12:58 PM:

Star and polyester stock are almost imposible to cut or tear by hand so if the film is tear apart is not polyester is vinyl acetate.

Posted by Kevin Clark (Member # 211) on June 24, 2018, 07:01 PM:

Hello Maurice

My advice is stick with the criteria you mentioned but just numbers 2,3 and 4 - as I stated in your other post I was nearly fooled into selling Mark my spare 16mm print of County Hospital which looked so much like polyester - translucent on the reel and flat as a pancake - but tested as acetate when torn at the start of the countdown leader and then successfully spliced with a cement splicer.

Kevin.

Posted by Maurice Leakey (Member # 916) on June 25, 2018, 10:29 AM:

Good advice, Kevin
The oft mentioned suggestion of holding the spool sideways up to the light certainly does not seem to be a reliable check for polyester.
I've proved it.

Posted by Terry Sills (Member # 3309) on June 26, 2018, 01:30 AM:

Maybe holding up to the light is not a check for polyester, but it is an excellent and very easy way to check for splices an film damage. My experience is that it works on all 16mm film base.

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