Re: [ARSCLIST] Moldy Tapes

[Martin Fisher <wmfisher@xxxxxxxx>]

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: peter@xxxxxxxxxxxxx 
  To: ARSCLIST@xxxxxxxxxxxx 
  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
  peter@xxxxxxxxxxxxx

  Tape restoration and disaster recovery since 1983

  -----Original Message-----
  From: Association for Recorded Sound Discussion List
  [mailto:ARSCLIST@xxxxxxx] On Behalf Of Steve Puntolillo
  Sent: Tuesday, July 10, 2007 12:31 PM
  To: ARSCLIST@xxxxxxxxxxxx
  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
  ========================================================