We had the pleasure of coming across several ¼” reels a few years ago that were contaminated with mysterious white crystals: http://cuttingarchives.com/tape-crystals <http://cuttingarchives.com/tape-crystals>
After a bit of investigating, the best explanation I could find was provided by Peter Brothers at Spec Bros:
"At various times, white powder or crystalline residue on magnetic tape has been identified as:
1) Cyclic trimers from the polyester base
2) Sodium or calcium impurities from the magnetic powder
3) Various fatty acids or sterates from the lubricant
4) Surfactants left over from the manufacturing process
5) Various external contaminants from exposure to "extreme" environments
The fatty acids and sterates will usually dissipate or be re-absorbed into the tape after a few days of exposure to a warm environment.
Most contaminants can usually be removed by the gentle and judicious application of small amounts of water, alcohol or a combination of the two.
Some residues may require other treatment but it depends heavily on whether the tape is acetate or polyester base."
Fortunately for us, a combination of light dusting with compressed air, gentle cleaning with a HEPA vacuum, and wiping with alcohol moistened Pellon cleaned the tapes right up. Once cleaned, the tapes did not have any issues during playback.
> On Sep 19, 2014, at 9:51 AM, Karl Fitzke <[log in to unmask]> wrote:
> Is this link working for you?
> Coincidentally, I just made contact with the Cornell Chemistry Dept yesterday. I had set this issue aside for a while.
> On 9/19/14 8:23 AM, seva, soundcurrent mastering wrote:
>> yep. login wall.
>> On Wed, Jul 23, 2014 at 5:18 PM, Richard L. Hess <[log in to unmask]>
>>> Hi, Karl,
>>> This is very interesting.
>>> The Wikipedia article discusses acidic fumes/vapors are emitted by PVC
>>> (the basefilm of some early 1940s and 1950s tapes) and polyurethane (a
>>> eidely used binder) as well as wood, cork, non-archival cardboard, paper,
>>> and cotton.
>>> It is good to know it's a salt, but, unfortunately, the photo is behind a
>>> login wall.
>>> On 2014-07-23 3:41 PM, Karl Fitzke wrote:
>>>> Still hoping to engage someone at Cornell with mass spectrometry
>>>> capability, but today Mycologist Dr. Kathie Hodge of Cornell Plant
>>>> Science generously put a few tapes under the microscope and gave us the
>>>> representative photo at the link below. We looked even closer and it
>>>> is surely some kind of salt.
>>>> Kathie also shared the finding with a snail taxonomist, who said that
>>>> this looks like Byne's disease.
>>> Richard L. Hess email: [log in to unmask]
>>> Aurora, Ontario, Canada 647 479 2800
>>> Quality tape transfers -- even from hard-to-play tapes.
> Karl Fitzke
> Audio Engineer
> Macaulay Library
> Cornell Lab of Ornithology
> 159 Sapsucker Woods Road
> Ithaca, NY 14850
> [log in to unmask]
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