I can verify Corey's experience regarding the #3M mag film issue (which
3M was aware, and worked hard to rectify).
A real nightmare, as it would tend to "hang" when going over the heads,
causing all kind of disturbances in the Davis tight-loop on the
Chicago Audio Works, Inc.
On 12/20/2015 1:15 PM, Corey Bailey wrote:
> I only have anecdotal evidence that Charlie Richardson's suspicions
> may be correct and it comes from the world of magnetic film:
> The vast majority of magnetic film, as we all know, was a tri-acetate
> base product and thus suffers from vinegar syndrome (VS) over time.
> However, one of 3M's last offerings was a polyester base, back coated
> product that yes, has the tendency to go SS. I have encountered the
> problem more than once with that particular type of mag film and all
> of it has been stored in the best of conditions. Other manufacturers
> offered polyester base magnetic film stocks that were not back coated
> and do not tend to go SS.
> Holiday Cheers!
> Corey Bailey Audio Engineering
> On 12/20/2015 5:24 AM, Tom Fine wrote:
>> I should also mention, Charlie wanted me to send the tape back after
>> the first transfer for "further processing." I decided, no, I want to
>> see how it holds up in the real (reel) world, over time, under
>> non-vault storage conditions.
>> -- Tom Fine
>> ----- Original Message ----- From: "Jamie Howarth"
>> <[log in to unmask]>
>> To: <[log in to unmask]>
>> Sent: Saturday, December 19, 2015 10:54 PM
>> Subject: Re: [ARSCLIST] One more sticky-shed data point - Richardson
>> treated tape
>> Very cool. Rad, scary, but if it holds up that's great.
>> Please pardon the mispellings and occassional insane word
>> substitution I'm on an iPhone
>>> On Dec 19, 2015, at 8:54 PM, Tom Fine <[log in to unmask]>
>>> Back in early 2014, I sent Charlie Richardson an old Ampex 7.5IPS
>>> alignment tape, which is on Ampex 406 tape, circa 1970. The tape was
>>> definitely sticky-shed, in fact the first couple of layers I wound
>>> out by hand pulled oxide to the adjoining backing layer. Richardson
>>> treated the tape with his "Rezorex" process, which apparently uses a
>>> chemical peel to remove the back-coat layer, which Richardson
>>> contends is the source point of sticky-shed. I transferred the tape
>>> in May 2014 with no problems, then put it on a shelf in ambient
>>> metro-NYC indoor environment. That first playback was on an Ampex
>>> AG-440B. I just rewound and played the tape again, this time on an
>>> Ampex 352. Still no sticky-shed evidence, and the audio was fine
>>> (test tones were 10dB below reference tone, for the most part,
>>> azimuth tones allowed stable adjustment). Richardson had left a
>>> little bit of the end of the reel with the back-coat still on, and
>>> that tape was solidly sticky-shed. I will keep on playing this tape
>>> once a year to see if it goes sticky again.
>>> I think a more scientific test of this process would require
>>> sacrifice of both a sticky-shed test tape and a high-fidelity music
>>> recording on sticky-shed tape. Although Richardson wants tapes not
>>> to have been previously baked and played, which he contends damages
>>> the tape, I'd want a reference transfer after one bake. Then let the
>>> back-coat layer be removed, and do a transfer with the exact same
>>> equipment and compare both measurements and careful listening, see
>>> if the chemical peel does any sonic damage. In the case of my old
>>> test tape, all I'm saying is that the tones are at the announced
>>> levels, and this tape could be used in a pinch to align a tape deck,
>>> although I'd want to bet on a modern MRL tape if it were for
>>> anything critical.
>>> One other thing. The tape with the backcoat removed is not as thin
>>> as I thought it would be. It seems to move through the transport
>>> just fine. I didn't observe any obvious edge-curl or country-lane
>>> motion, and it fast-winds just fine through all the static guides on
>>> an older Ampex transport.
>>> I'd want to do more testing with very familiar high-fidelity music
>>> recordings to make sure the process doesn't do any damage to audio,
>>> but for at least a year and a half, it does seem to prevent a return
>>> of sticky-shed's mechanical symptoms.
>>> -- Tom Fine