Re: [AV Media Matters] Re-Evaluating Tape Mastering Stock

[Mick_Newnham@screensound.gov.au]

>Any feedback on storing as pancake vs. NAB metal reels? We have been
thinking about storing as pancake with a micro-chamber acid free paper
between tape pack and shipper backing as scavenger for any out gassing
that may not have been lost in curing process. I happen to be a big fan
of the old 3m black plastic shippers - comments on other containers for
long term storage?<

More from a storage point of view, I have recently been looking at the
"passive" removal of decomposition by-products from film cans.  One of the
more useful references has been the Indoor Air Pollution Working Group web
site: http://hjem.get2net.dk/ryhl/iap.htm.

Of particular interest are the papers from Dr Mike Morris, University of
Cork who has been studying the use of passive sorbents (scavengers).  In a
1998 paper Dr Morris states "Sorbents for adsorption are inexpensive, have
a high surface area, can normally be regenerated, and require non-toxic,
inexpensive housing. However, it should be noted that there is no point in
using a bed of sorbent as the kinetic energy of gases is not sufficient to
force the gas into the sorbent unless there is a flow (positive
pressure)."

This would indicate that unless there is some form of air
movement then the
effectiveness of scavengers is limited.  I have yet to start looking at
scavengers inside a system but my recent work has been looking at
ventilating film cans and certainly the movement of air through a can
produces substantially lower acid level in the can environment and the the
film than even a vented can with no air movement (quite logical really).

I would suggest then that adding the micro-chamber acid free paper may be
more expense than value.

Mick Newnham
Engineering and Research Group
Preservation and Technical Services
ScreenSound Australia