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

[joe salerno <salernoj@swbell.net>]

Please define forced evaporation. Do you mean fans? Heaters?

Joe Salerno
Video Works! Is it working for you?
PO Box 273405 - Houston TX 77277-3405
http://joe.salerno.com
Fax: 603-415-7616
----- Original Message -----
From: <smolians@erols.com>
To: <AV-Media-Matters@topica.com>
Sent: Monday, April 03, 2000 6:17 PM
Subject: Re: [AV Media Matters] metal vrs wooden shelving for VHS tape

>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