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On 11/06/04, James Lindner wrote:
> Years ago it was considered "good engineering practice" to keep the
> tapes in the plastic bags that they were shipped in by the
> manufacturer. I do not know the derivation of that idea - but that is
> what I was taught as a tape operator in my youth. When I got started
> in this field, I questioned that notion - so I kept condition
> information about tapes that were being cleaned, and I tried to
> correlate whether tapes that were in a bag were in fact in better
> shape. It was not a truly scientific study because I did not have a
> way to empirically measure how dirty tapes were in the first place,
> and I did have other people cleaning tapes then me - so what may have
> been slightly dirty for one person may have been considered medium
> dirty for another. Nevertheless - I could not every find any
> meaningful correlation between binder degradation and tapes enclosed
> in plastic bags that should have provided some level of vapor barrier
> protection. The notion that I came up with to explain this is that
> over long periods of time the RH inside the bag (unless it was sealed
> and virtually none were) and outside the bag would have equalized -
> and if anything the vapor barrier would have provided a bit of latency
> against humidity cycling (for better or worse). But this was a
> hypothesis. In fact I could find no demonstrable correlation.

It's a brave man who admits that his experiment produced no conclusion.
;-)

I would have thought that if the bag was just folded over, the humidity
inside would equal that outside after a few hours. Water vapour can
diffuse through microscopic holes.

Regards
--
Don Cox
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