8mm Forum: Why Acetate, Why Poly?

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Posted by Winbert Hutahaean (Member # 58) on October 10, 2007, 04:42 AM:

I knew that there are at least 2 stocks used on printed film, Acetate and Polyester (any other stock? OK, I knew Nitrate stock but this one has been discontinued due to the safety)

Kevin F once told that Acetate can get VS and Poly cannot.

a. So why there is Acetate and what is the benefit of it?

b. Any new movie is printed on Acetate?

c. Is this about the time where Poly came later?

d. Is any Kodachrome/Ektachrome from Kodak made of Poly no matter what year they are from?

sorry for silly questions but they are my curiosity.

cheers,

Posted by John Whittle (Member # 22) on October 10, 2007, 05:36 PM:

First there was nitrate, but when Kodak wanted to introduce home movies, a slow burning film was needed. The first was diacetate, early Kodachrome was another base, then then triacetate started being used in 35mm and subformats. The change in 35mm stocks came in the early 1950s.

Estar (Kodak's name) and other poly base materials also date way back. Originally it was more expensive than acetate and harder to coat. Also if any problem happened in processing or projetion, the machine was more likely to break rather than the film. Ektachrome was made on Estar base at 3000 pitch for high speed cameras used in research. The widespread use came when 35mm prints were made on the stock and then subformat (such as Super8).

Since you can't solvent splice Estar, you must tape splice it and the liquid dispersion sound stripe wouldn't work.

Now days, very few stocks are coated on acetate, and like black and white positive, are usually special order materials. 35mm Color Negative camera film are still acetate.

The Estar material wears tooling faster (such as slitters and perforators) as well.

John

Posted by Osi Osgood (Member # 424) on October 10, 2007, 10:46 PM:

Good ole John, always a great source of info.

Curious, which tended to scratch easier, acetate or poly?

I may be way off on this, but was nitrate film cellulose based? I ask because plastics didn't come into widespread use until the 1930's. I might be off on my history.

Posted by Chip Gelmini (Member # 44) on October 10, 2007, 11:39 PM:

Nitrate is still available. It's better than a dayrate. [Big Grin]

Posted by John Whittle (Member # 22) on October 11, 2007, 09:10 PM:

Yes nitrate was cellulose based and in fact it's proper name is cellulose nitrate. It was also used for many things other than film. Kid toys were made of it, Christmas tree decorations (image a tree with candles and cellulose nitrate ornaments!) and lots of clear sheeting material. Acetate materials were known long before they became film base materials as well. In fact the early di-acetates date back to the 20s or earlier.

John

Posted by Kevin Faulkner (Member # 6) on October 12, 2007, 03:37 AM:

Wow! I had no idea that stuff was used for kids toys and Christmas decorations. I bet there were loads of house fires because of that material.

I would think that stuff is well banned now, from all walks of life.

Kev.

Posted by Lee Mannering (Member # 728) on October 12, 2007, 04:27 AM:

This is fun reading..

What is cellulose nitrate?
Cellulose nitrate is the plastic commonly used for film-base
photographic materials (stills, movie and X-ray films)
manufactured up to the early 1950s. It contains a high proportion of nitro-cellulose, otherwise known as celluloid.
Cellulose nitrate is extremely flammable.
More modern film is acetate or polyester-based, which is not so
hazardous.
Why is cellulose nitrate film dangerous?
It is the nitro-cellulose that makes cellulose nitrate-based film so
dangerous to store and handle. It is hazardous because:
it can start to decompose and become unstable at
temperatures as low as 38°C, giving off large quantities of
poisonous gases, which could cause an explosion. Warmth
and humidity (moisture) accelerate this decomposition;
it catches fire very easily and burns extremely quickly, with a hot and intense flame.

From the Health & Safety Exec.

Still have a few 35mm Nitrate prints myself in the archive as do my friends which we run from time to time. These have been well looked after obviously and put some of the VS 16mm prints to shame that have gone in the bin.

Posted by Adrian Winchester (Member # 248) on October 12, 2007, 05:51 PM:

b. Any new movie is printed on Acetate?

I think it's rarely used nowadays, but the German lab that prints Classic HC releases uses it, for some reason.

Posted by Steve Klare (Member # 12) on October 12, 2007, 06:14 PM:

Nitrate Based Film:

http://www.youtube.com/watch?v=-Tdpuhz83hg

-'nuff said!

Posted by Bill Brandenstein (Member # 892) on October 14, 2007, 03:51 PM:

Or try this one from the Mother site proving that the flames of nitrate cannot be doused:

http://www.film-tech.com/warehouse/wareview.php?id=1265&category=3

Posted by Lee Mannering (Member # 728) on October 16, 2007, 11:37 AM:

Nitrate can also be used for browning off your sausages on a hot summers day.
[Eek!]

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