Re: [AV Media Matters] metal vrs wooden shelving for VHS tape

[smolians@erols.com]

I did the post-flood disaster survey and recovery plan for the Boston Publc
Library about 2 years ago.  The shelving for the sound archive, stored in
the basement, was wooden. A water main had burst and flooded to a height of
about a foot when first inspected.  All records and tapes above the bottom
shelf were dry.

The following day, the water had wicked up the wood and soaked the bottom of
the materials on the next shelf.  It continued to the following one in some
sections.  The basement was pumped out, of course, but the wood remained
damp for some time.  The humidity was reduced by forced evaporation.  Anyone
for moldy oldies?

At last count, 77,000 records were lost.

Steve Smolian

-----Original Message-----
From: kbradley@nla.gov.au <kbradley@nla.gov.au>
To: AV-Media-Matters@topica.com <AV-Media-Matters@topica.com>
Date: Monday, April 03, 2000 5:32 PM
Subject: RE: [AV Media Matters] metal vrs wooden shelving for VHS tape
storage

>>Does anyone have data on magnetizing of metal shelving from long
>term
>>storage of VHS cassettes?  Any suggestions on how to mitigate?
>
>
>I did some measurements on metal shelves using a magnetometer to see if
>there were any fields strong enough to damage a tape.  The short answer is,
>I couldn't find any.
>
>On some of the corners of the folded metal shelves at zero distance the
>highest field I have ever found was around 10 oesteds DC, which is about a
>quarter of what the Knight article in the IASA phongraphic bulletin defined
>as a problem, and about half of what we at the NLA adopted as a minimum
safe
>standard.  Given that the field strength drops in inverse proportion to the
>square of the distance, the actual strength at the first layer of tape is
>much much smaller.  So we concluded, that while it is feasable to magnetise
>a steel shelf to such an extent that the residual field may be damaging to
a
>low coercivity tape, no-one is putting that sort of effort in.  I still
>borrow a magnetometor and check new shelves occassionally though.
>
>Wood shelves have a whole heap of potential problems associated with
exuding
>gaseous and other substances which your average conservator can tell you
>about.  Metal are a better bet.
>
>Kevin Bradley
>a/g Manager: Digital and Audio Preservation Resources
>National Library of Australia
>Canberra   ACT 2600
>AUSTRALIA
>
>Tel:  +61-2 6262-1381
>Fax: + 61-2 6262-1653
>Email: kbradley@nla.gov.au
>NLA home page: http://www.nla.gov.au
>Change is inevitable, except from a vending machine
>
>> ----------
>> From: mha@durab.com[SMTP:mha@durab.com]
>> Sent: Saturday, 1 April 2000 7:33 AM
>> To: AV-Media-Matters@topica.com
>> Subject: [AV Media Matters] metal vrs wooden shelving for VHS tape
>> storage
>>
>> Does anyone have data on magnetizing of metal shelving from long term
>> storage of VHS cassettes?  Any suggestions on how to mitigate?
>> thanks
>> mark
>> Mark Hopkins + Associates
>> 28 Warland Avenue
>> Toronto ON M4J 3G2 CANADA
>> tel: 416-421-5369
>> fax: 416-421-7788
>> e-mail: mha@durab.com
>>
>> Monitors Comment:
>> This comes up now and then - the short answer -get  Metal Shelves not
>> Wood.
>> VHS tapes will not magnetize shelving - but people usually ask about
metal
>> shelving demagnetizing VHS cassettes - that is not an issue either unless
>> 1. There is a VERY strong magnetic field CLOSE to the tapes for a LONG
>> TIME
>> 2. The shelves have previously been used with rare book bookends that
have
>> VERY STRONG magnets that will sometimes magnetize the shelving - but
>> whether
>> the field strength is strong enough to do anything is questionable even
in
>> that case.
>>
>> jim