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Re: [ARSCLIST] Acetate tape discolours tape box

In a message dated 10/17/2006 3:10:45 PM Eastern Daylight Time, 
tflists@xxxxxxxxxxxxxxxxxxx writes:
Hi Bev:

OK, this is great. Now I understand a lot better. Thanks!

The key seems to be, better to get the tapes transferred sooner.

One big question remains -- why do some acetate backed tapes seem to get this 
worse than others? 
Again I say that I've never run into a vinegar-smelly AudioTape reel but 
often find this with Scotch 
111 and even 131.

If someone is set up to look at breakdown amounts or pH or whatever you 
measure to see if vinegar 
has set in and how bad it is, I can probably dig up a few small samples of 
both Audiotape that is 
not obviously acidic and Scotch tape that is.

-- Tom Fine

PS -- I am told that Scotch and Audiotape 35mm mag-film from the late 50's 
into the 60's has a very 
bad tendancy to develop this problem and the film does shrink and curl. Now, 
why is this material so 
likely, indeed guaranteed to develop this and break down? Is it because of 
the thicker film base 
made of acetate, thus more concentrated material to develop and self-feed on 
the syndrome?

My recent experience with film is that the end point is complete breakdown of 
the acetate base leaving shriveled, cracked emulsion over a base that 
disintegrates in contact.  However it is extremely variable. I have many films from 
the 30s that show no deterioration but many from the 40s that are completely 
unusable. W.W.II morale films seem to be the worst. Castle home movie reels are 
remarkably durable. As usual, the quality of the materials and processing has 
a lot to do with it. 

The thicker base of film retains the acetic acid better than tape. The role 
of iron oxide is confusing. For film, it is recommended to avoid rusted reels 
and cans, and mag film is supposed to be especially susceptible. However tape, 
with its intimate contact with iron oxides, seems less affected than film. I 
suspect that ventilation, storage in unsealed cardboard boxes instead of cans, 
is a major factor.  Why were films put in cans in the first place? The Castle 
films and other home movies were usually distributed in cardboard boxes and 
they have held up well.

I've been looking into the Kodak Molecular Scieves 
http://www.kodak.com/US/en/motion/support/technical/molecular.jhtml and have obtained samples. There are 
a number of strange remedies on the Internet. Has anyone tried the magic 
potion at http://members.optushome.com.au/picturepalace/Vinegar%20Syndrome.html?  
However it seems that storage in open reels or light, cardboard boxes in a 
humidity controlled, ventilated environment would be just as effective.

Extreme dryness and heat will produce the same curling and brittleness 
symptoms as vinegar syndrome in film and tape. Humidification is recommended for 
film ... except that it exacerbates the vinegar syndrome deterioration once it 
starts. Temporary storage in a can with damp blotting paper may make a film or 
acetate tape recoverable from extreme stiffness and curl, but mold and 
accelerated breakdown is an immediate risk.

Mike Csontos

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