Film-Tech Forum ARCHIVE: Archive film projection with high acid level

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Posted by Anhtu Vu (Member # 7689) on 04-03-2018, 03:01 PM:

Hi all,

I just want to get some feedback from people who works in an archive environment.

We will be projecting some old / rare 35 mm films. They are in fair condition with high acid level.

- Can the film contaminate the projectors ?
- If so, any special procedures for cleaning the projectors afterwards
- I would like to hear from experienced archivist how they deal with the above scenarios

Thanks

Posted by Paul Gordon (Member # 3320) on 04-03-2018, 03:29 PM:

Anhtu,

You don't have to worry about contamination. Just clean your projectors like with any other film. You may have to worry about brittle film, high shrinkage, and focus issues though.

Posted by Anhtu Vu (Member # 7689) on 04-03-2018, 03:38 PM:

Hi Paul,

Thanks for the info.

I'm just curious as i'm getting different point of view on this subject...is there a reason why contamination cannot occur on a film projector but do happen if i store a film in the same contaminated metal can ?

Do you, at the Ottawa Archive, have some sort of guidelines when it comes to accepted acid and shrinkage level ?

Thanks again,

Posted by Monte L Fullmer (Member # 2797) on 04-03-2018, 05:10 PM:

Only contamination I know about is with nitrate film where this stock needs to breathe and under strict temperature and humidity controls.

With cans having nitrate stock in it and not allowing air circulation along with the required temperature and humidity conditions, this stock would begin to deteriorate and break down.

Acetate shares some of the degradation when the stock can't breathe and also the same temp and humidity conditions and you get the classic vinegar odor, or commonly known as Vinegar Syndrome with the acetate breaking down, releasing acetic acid.

Yet, that's the key is to knock a few holes on the edge of the can so the stock can breathe along with keeping the stock in controlled atmosphere conditions.

Just keep the machine clean and have a great presentation.

Posted by Donald Brown (Member # 5427) on 04-03-2018, 05:47 PM:

In the late '80s, I bought the contents of an old drive-in theatre in Shelburne Falls, Massachusetts. The facility was rather spartan in its appearance and design. Among the equipment remaining on site were 60 single spool cans of old nitrate stock, historic footage of local events from Connecticut and Deerfield River Valley communities. While some of the material had significantly deteriorated, much was in exceptional condition! I recall remarking that the decades old spools, stored in a less than optimal environment, were in better condition than many of the current prints circulating at the time!
Nearly 25 years later, while removing debris from under the screen at the Skowhegan Drive-In Theatre in central Maine, I located 7 single spool cans of vintage intermission footage from the '50s and '60s. Discounting damage from decades of use, the acetate stock was in surprisingly good condition considering its surroundings, which included inches of accumulated racoon feces.

Posted by Bill Brandenstein (Member # 7758) on 04-04-2018, 02:35 AM:

Seems to me that any acetic acid that comes into contact with metal projector parts while running a VS print would soon disperse into the air. Can anyone present an argument against that? Otherwise, yes, clean as normal and have fun with the focus knob.

Posted by Jerry Axelsson (Member # 3175) on 04-04-2018, 09:30 AM:

We avoid running a 35mm print which is shrunk beyond 0,8%
If we should run a vinegar print, we clean all parts of the machine, film spools etc. with alcohol.

A print suffering from severe vinegar is also what I consider a working environment problem, which should be avoided.

Posted by Monte L Fullmer (Member # 2797) on 04-04-2018, 02:06 PM:

quote: Jerry Axelsson
A print suffering from severe vinegar is also what I consider a working environment problem, which should be avoided.

Along with with being totally unplayable since the gassing of acetic acid off the acetate stock, the stock itself becomes totally brittle and fragile.

Posted by Carsten Kurz (Member # 5396) on 04-04-2018, 05:18 PM:

Come on, stock suffering from vinegar syndrome is not actually pouring out vinegar in gallons. Every booth set up properly should have enough air throughput to get rid of molesting gases. Just clean the projector normally with alcohol. Shrinking, though, is much more of a potential problem (aside from other aspects already mentioned). Compare a piece of shrinked footage with a piece of current/less dated modern print (e.g. a piece of leader or trailer from a more recent release).

From another thread, I also heard the max 0.8% number. That is a one perf hole slip over 93 holes if I remember right.

I found a long fluorescent/LED tube practical for doing these checks. You can stick a known good piece of film onto it and add some markers. 'Real' fluorescent tubes are better suited, as they are glass based and do not shrink themselves (other than LED retrofit tubes, which commonly use plastic tubes).

- Carsten

Posted by Mitchell Dvoskin (Member # 751) on 04-04-2018, 05:51 PM:

> is there a reason why contamination cannot occur on a film projector but do happen if i store a film in the same contaminated metal can.

1. The projector is not air tight like the can. The acetic acid fumes do not build up. Cleaning the film path removes any acetate dust.

2. Acetate dust left behind in the can.

3. The metal can does not absorb the acetic acid, but rather any paper/cardboard in the can does.

4. Rust attracts moisture, and moisture hastens vinegar syndrome, so if the can is rusting it is bad no matter what has previously been in it.

Thoroughly washing (and drying) a metal can will eliminate this issue, although ideally you should be using a vented archival plastic cans.

Posted by Stephan Shelley (Member # 8587) on 04-04-2018, 07:31 PM:

One thing with vinegar syndrome is the film getting a sever curl to it.At first it is focus issues as the film is not flat in the gate but as it progress it will no longer stay on the sprockets.