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: >>Hello, >> >>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 > http://is.gd/kqVy or found here: > http://www.richardhess.com/tape/history/index.htm > 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 > http://mint.ua.edu/pdf/reviews/Spring%202002/Pollution%20Prevention.pdf > http://www.research.ibm.com/journal/rd/302/ibmrd3002H.pdf > > 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: http://www.richardhess.com/tape/contact.htm > Quality tape transfers -- even from hard-to-play tapes.