Date:Wed, 11 Jul 2007 13:41:41 -0500
Reply-To:Martin Fisher <[log in to unmask]>
Sender:Association for Recorded Sound Discussion List
<[log in to unmask]>
From:Martin Fisher <[log in to unmask]>
Organization:The Center for Popular Music
Subject:Re: Moldy Tapes
Comments:To: Association for Recorded Sound Discussion List <[log in to unmask]>
Content-Type:text/plain; charset="iso-8859-1"
Will do Peter. Thanks!!
Martin
----- Original Message -----
From: [log in to unmask]
To: [log in to unmask]
Sent: Wednesday, July 11, 2007 1:11 PM
Subject: Re: [ARSCLIST] Moldy Tapes
Martin:
I hope your tap water comes untreated. If it contains chlorine, and you are
keeping the originals, there could be some long-term damage. Chlorinated
water EATS tape. Even if the project is low budget, I strongly suggest you
get some distilled water for the "wet" portion of your cleaning process.
Peter Brothers
SPECS BROS., LLC
973-777-5055
[log in to unmask]
Tape restoration and disaster recovery since 1983
-----Original Message-----
From: Association for Recorded Sound Discussion List
[mailto:[log in to unmask]] On Behalf Of Martin Fisher
Sent: Wednesday, July 11, 2007 10:31 AM
To: [log in to unmask]
Subject: Re: [ARSCLIST] Moldy Tapes
Hi Guys,
Thanks for all the input on the moldy tape query.
The tapes in question are 7 inch X 1/4 inch reels of field interviews done
in the eighties. The boxes don't necessarily match the tape stock since
most of the tapes are tails out and I think the reels and boxes were
shuffled by using the former supply reel as takeup for the next go-round.
Stock seems to consist mainly of Scotch 206, Maxell XL1 35-90B and a generic
nonbackcoated 1.5 mil tape on smoky, very nonprecision and nondescript reels
in white boxes. (I've run into this same white box type stuff before at the
Tennessee State Library and Archives.) No acetate stock encountered so far.
I've cleaned and transferred about ten out of fifty by doing an initial out
of the box cleaning of the reel and pack and outer turn layers, then a fast
forward "dry wipe" followed by a spot wet cleaning (and drying) using tap
water on heavily contaminated areas. (Not the most scientific method but
this is a low budget job and seems to work fine for transfer as all of the
tapes play fine with no perceptible problems.)
Best!!
Martin
----- Original Message -----
From: [log in to unmask]
To: [log in to unmask]
Sent: Tuesday, July 10, 2007 1:35 PM
Subject: Re: [ARSCLIST] Moldy Tapes
Steve:
As Eric mentions, long-term-low-humidity exposure will reduce "sticky
shed".
It just takes a lot longer than "baking" and has some other side effects
on
really bad tapes: if the tape is badly enough hydrolyzed that it has
"blooming" [actual "puddles" of oligomer residue] on the surface, it can
cause cross-linking of the oligomers without re-absorption into the binder
matrix. This can result in areas of hardened polymer on the surface of
the
tape and, in the most severe cases, can "weld" wraps together. Note:
"blooming" is most common on 2" tape.
One of the benefits of low-humidity treatment (especially when combined
with
temperature reduction) is that the primary vector of expansion and
contraction of magnetic tape with either humidity or temperature changes
is
THICKNESS. Unfortunately, if you reduce humidity by "baking", the
reduction
in tape thickness from the reduced humidity is off-set by the increase in
tape thickness caused by the raised temperature.
Because of this, low humidity treatment will shrink the thickness of the
tape and loosen the pack while it is also reducing the effects of "sticky
shed". When treating tapes with both fungus and sticky-shed for shorter
times (8-10 days), the slight reduction of the sticky-shed, along with the
loosening of the pack, can often result in a tape that can be slowly
unwound
for cleaning. Once the majority of the fungus residue is removed, a tape
with bad sticky-shed can then be baked if needed for playback. The order
of
treatment (heat, cold, low humidity, vacuum, dry wiping, wet wiping, etc.)
and the number of treatments depends on the specific condition of each
tape.
As Eric also points out, the actual removal of the mold is another matter
and can present serious health hazards if not done under controlled
conditions.
Hey- no one said that restoring tape "the right way" is easy.
Peter Brothers
SPECS BROS., LLC
973-777-5055
[log in to unmask]
Tape restoration and disaster recovery since 1983
-----Original Message-----
From: Association for Recorded Sound Discussion List
[mailto:[log in to unmask]] On Behalf Of Steve Puntolillo
Sent: Tuesday, July 10, 2007 12:31 PM
To: [log in to unmask]
Subject: Re: [ARSCLIST] Moldy Tapes
Hi Peter --
Peter @ specsbros wrote:
> To drive the mold into dormancy, it is necessary to remove
> moisture from the mold, itself, and the tape. This can take
> up to 8 - 10 days of holding the tape in a controlled
> environment of around 30% RH. It can be done somewhat faster
> at lower RH and can take quite a lot more time if the RH is higher.
> (Note: baking is not recommended as, while it can sometimes
> work, it can also cause problems with moldy tape- depending
> on the type and amount of mold, baking can harden the
> mold-related residues and "bake" wraps together).
So, it sounds like you are recommending a low-humidity exposure at normal
temperature for several days followed by cleaning.
What if the tape also has a bad case of SSS? It seems as though you would
be
stopped. You can't spool it to clean it because it has SSS and you can't
bake it to spool it because it has mold.
What do you recommend?
Thanks,
-- Steve
========================================================
Steve Puntolillo
Sonicraft A2DX Lab - Ultimate A_nalog 2 D_igital X_fers
http://www.sonicraft.com
========================================================
