8mm Forum: Film Cement

This is topic Film Cement in forum 9.5mm Forum at 8mm Forum.

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Posted by Brian Collins (Member # 761) on March 13, 2009, 04:50 AM:

Does film cement loose it quality over a period of time, has it a shelf life or will it still be fully effective regardless, I have had to repair some films and on some have had a devil of a job getting to stick firmly or maybe it is the type of film, especially some 9.5s.

Posted by Dino Everette (Member # 1378) on March 14, 2009, 12:22 AM:

yep, it most definitely loses its ability to adhere over time. 9.5mm film will adhere perfectly from cement that is still good. The type of film wouldn't matter unless you were trying to cement new polyester or estar film to acetate (both diacetate or triacetate) as polyester film needs an ultrasonic splicer which is like a gajillion dollars or tape splices.....For 9.5 I actually have really good luck using 16mm splicing tape and an exacto blade because with the right placement it will cover 2 whole frames and one sprocket so that it is not noticeable when it passes through like the scraped section on cement splices.

Posted by John Whittle (Member # 22) on March 14, 2009, 06:14 PM:

If you go though old books you'll sometimes find formulas for film cement. It was not uncommon in the silent era for projectionists to make up their own. Many of these chemicals are known by other names today, but the major part is acetone. You often can "revive" an old bottle of film cement if you have to with a little fresh acetone.

In the lab we used to dump film cement out at the end of each shift or at lunch and start with fresh (I'm sure that would be totally illegal today with current laws).

Remember to wait to open the bottle until you're ready to apply the cement and quickly return the brush/cap and screw it on to extend the life of the cement.

If you can, buy a large can (quart) and use it to fill you small bottle(s). That should give you a supply for life.

John

Posted by Bill Brandenstein (Member # 892) on March 16, 2009, 12:16 AM:

John, I've seen bottles of cement turn yellow/brownish. A couple of these are decades old, but one I have thats only a few years old is now doing it.

Is it our local smog?

Posted by John Whittle (Member # 22) on March 16, 2009, 04:01 PM:

No it happened in Seattle where I grew up as well. I think it's a reaction of light to the ingredients in the film cement.

Here's a quote from a 1917 book "How to Make and Operate Motion Pictures", "It will be seen that amyl acetate forms a cement by dissolving the surfaces of the pieces of film to which it is applied. Many workers prefer to use a cement already prepared. This may be bought, or it may be made by adding to 1 oz of the amyl acetate a strip of film about 6 in. long, clean and free from emulsion. Be sure the strip of film is clean, then cut it up, and place in the solvent. It soon dissolves, when it is ready for use, being applied with a camel-hair brush as before."

"Another good cement, but one that dries more slowly, is a colution of a 6-in strip of film in a mixture of 1/2 oz of acetone and 1/x oz of amyl acetate. If too thin, add more celluloid; if too thick , add more solvent.

When repairing non-flam film this not being soluable in amyl acetate, chloroform is the solvent to be employed. This may be used alone, as already explaine; but owing to its volatile nature it is better converted into cement by adding fragments of the non-flam film until the proper consistency is obtained, a matter that a few simple experiments will easily decide. Special cements for non-flam films are obtainable."

Laws have changed since 1917 and availablity of various chemicals may be restricted, so this is provided for its historical information only.

Kodak professional film cement was patented in 1953. Here are the ingredients:

Acetone 20.5 percent
Dioxane 19.0 percent
Methylene chloride 55 percent
Methold alcohol 3.7 percent
Nitrocellulose 1.5 percent
Ethyl Alcohol .3 percent

Posted by Bill Brandenstein (Member # 892) on March 17, 2009, 12:04 AM:

As always, John, you are a source of wonderful and valuable information. Thank you for this kindness!

Posted by Brian Collins (Member # 761) on March 17, 2009, 08:02 AM:

Thanks gents for your input, learn something new every day on this site. [Smile]

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