bagging tapes

[Gkar]

I believe that I read somewhere, maybe here, that one should not bag acetate tapes, mylar OK, but not acetate, is this correct?

[Bruce B]

Bag?? or do you mean bake? No, you should not bake acetate tapes.

[Gkar]

no, bag, like put reel of tape in a plastic bag to help preserve, keep from dust, dirt, foul air, etc... and I mean the tapes, not the boxes, I have 10 inchers, mostly maxell's, that came with bags...

[ironbut]

With acetate tapes you should definitely never bake them!

As far as using some sort of bag to store the tape/reel in, it not advised. This isn't really because an acid free bag does any harm but rather, the cardboard box tends to be good for reduction of vinegar syndrome which will eventually ruin the acetate backing of the tape.
Vinegar syndrome was first discovered with old acetate movie film. Those were almost always stored in metal cans and the acid that's released by the breakdown of the acetate accelerates the process. The film would sometimes become so brittle that it would fall into shards if handled.
The archivists wondered why it was that acetate audio tape didn't meet the same fate even when the audio products were older than some of the fated film stock and were stored in the very same vaults. The answer was found in the boxes that showed a shadow of the tape reel inside the box. Sometimes when cue sheets or other sheets of paper were in these boxes, they would show the same "shadow".
It turns out that the cellulose acts as a buffer and neutralizes and absorbs the acid that's released.

So, in general, acetate tapes are subject to problems related to drying. Quite the opposite of sticky shed tapes which do benefit from baking. In fact, a common treatment for acetate tapes who suffer from LOL (loss of lubricant) is placing them in a high humidity environment.

[Gkar]

not sure how "bagging" was thought to be "baking", but as you said, Steve, no bagging for acetate tapes, but OK for polyester, yes?  I know what you mean about the "shadow" in the boxes or on paper inserts, I thought that may have been caused by the acid in the paper box construction, but as you say, it is the acid in the acetate tapes.  So, by that reasoning, putting in a slip of buffered cardboard would help the acetate tapes out more than the paperboard boxes the tapes are in.  As a small-time comic book collector, the acidification of the comic pages is a problem that is being solved with buffer paper products used in paper archiving, sounds like acetate tapes may also be helped by that same solution...

[Gkar]

well, Steve, I would have to say that your supposition that it is the acetic acid in acetate tapes that is causing the "shadow" effect may not be correct.  I have several boxes with "shadowing" that are absolutely polyester tapes, some of these boxes show heavy shadowing.  I am of the mind that it is the acid in the paper of the paper board boxes that is causing the shadowing, something noted in my comic collection area...

[ironbut]

Hey Randy,
Actually, it's not my supposition but something I learned from tape restoration professionals such as Richard Hess. Here's a link (see bottom of the page):

http://richardhess.com/notes/page/6/

BTW, if you've never checked out his site, there's tons of great info on magnetic tape. Richard's paper " Tape Degradation Factors and Challenges Predicting Tape Life" is accepted and used by most large institutions such as the Library of Congress.

[Gkar]

Thanks, Steve, I'll check that out!

[Gkar]

Hi, Steve, there was a pic of a tape from a white box, that certainly looks like the tape is outgassing acid and stained the box!