3M also had cheapo "Highlander" brand tape for a while. I'm not sure if that was stuff that didn't 
meet spec or if it was 3M's last generation of brown-oxide, no-backcoat duplicator grade tape.

3M spinoff Imation also used the Highlander brand for cheapo floppy discs in the 1990's.

My experience with olden days Shamrock (brown-oxide acetate and early polyester days) is that it's 
not destruction-prone like some tape of that vintage but it usually country-lanes all over the place 
and so good playback of well-recorded music in hard. Most of what I've dealt with, though, is 
half-track voice-grade stuff so no biggie that the tape quality isn't great. Like I said, at least 
it's not self-destructed like vinegar-prone Scotch 111 and Kodak tapes. BTW, "full quality" Irish 
tape isn't much better, in my experience. It brings to mind the old Dennis Miller routine: "Just 
what do you have to do to get kicked out of Guns 'N Roses?" Just what did a batch of tape have to do 
to get badged Shamrock instead of Irish?

-- Tom Fine

----- Original Message ----- 
From: "Richard L. Hess" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Sunday, February 22, 2009 7:39 AM
Subject: Re: [ARSCLIST] Ampex 456 and Shamrock 041 Manufacturing Specs?

> At 06:59 PM 2009-02-21, Sarah Norris wrote:
>>I'm looking for any manufacturing information available about Ampex 456 and Shamrock 041 tape. 
>>Anything would help, including manufacturing dates and anything known about materials or 
>>formulations used.  All information and references are much appreciated.
> Hello, Sarah,
> What an interesting question. May I suggest that you read my recent ARSCJ paper
>    or found here:
> if you haven't already for background and some chipping away at the problem.
> Michael Biel provided a more in-depth analysis of the Shamrock tape that I could have, but his 
> explanation expands on what I would have said, which is basically, Shamrock tape is anything that 
> didn't meet spec that might still show some ability to record and play back. 3M/Scotch did this 
> too with Melody tape, but when the FTC required location of manufacture to be placed on the box, 
> 3M stopped selling the stuff (at least in the U.S.) but Orradio/Irish/Ampex/Quantegy (that's the 
> lineage of the plant) proudly put Opelika, Alabama on the boxes. Think of it this way, selling 
> "seconds" (or "thirds" or "fourths") was a LOT cheaper than paying the trash man to haul it away.
> As to 456, it is the poster child for Sticky Shed Syndrome (SSS), however, all tape manufacturers 
> seemed to have created batches of tape which suffered from this. In discussing this recently with 
> Ric Bradshaw, a PhD chemist and tape expert, he said that polyester polyurethane is a good choice 
> for a binder, but the reaction has to be controlled. He also said that crosslinking may not have 
> been the correct choice to achieve the best long-term performance (he has yet to elaborate on that 
> to me).
> Another thing I think we know is that there were oligomers and other remnants of the manufacturing 
> process which may not have completely reacted remaining in the tapes when they were shipped. The 
> incomplete reactions and the excess component parts MAY be a contributing factor to tape 
> degradation and could very well explain the batch-to-batch variations we've seen from all 
> manufacturers.
> Some hints can be teased out of this and related papers
> I do have the reference somewhere to the typical family of polyester polyurethanes probably used, 
> but can't spend any additional time at the moment on this and the above two were what I could 
> quickly find in Google. The second one has two authors that deserve to be noted Bradshaw and 
> Bhushan.
> As to manufacturing specs, much of this lived in the minds of the operators, I suspect, who are 
> now long-gone. Some of the people from Redwood City may know something, but they are all getting 
> on in years and I suspect most if not all of the documentation is well-recycled. The real details 
> were considered trade secrets and even some people who are still around are loathe to discuss all 
> the details.
> On the other hand, the lack of control and the us-vs-them attitude that may have existed at some 
> level between Opelika and Redwood City cannot be ignored as factors. The folks in Opelika were 
> making tape before being bought by Ampex and that could be a root of some of the issues.
> Cheers,
> Richard
> Richard L. Hess                   email: [log in to unmask]
> Aurora, Ontario, Canada       (905) 713 6733     1-877-TAPE-FIX
> Detailed contact information:
> Quality tape transfers -- even from hard-to-play tapes.