Why Did Ampex Change Tape Formula?

bmg

Member
Taking a break from baking (tapes, not bread), I put up an old Deutsche Grammophon reel of Sitar Music From India from 1968:
1658271855727.png
I was amazed at how great it sounded, and was reminded of Ampex's near monopoly in the pre-recorded tape market of the 60's when I saw their logo on the label.
This made me wonder why on earth did they change their tape formula?
This one played through perfectly, with no issues at all (a far cry from what I'm dealing with lately.)
 

jamesperrett

Active member
Legend has it that one of the raw materials was derived from whale oil which was impossible to get hold of from the mid 70s onwards. I'm not sure how true this is though.
 

rob aylestone

Well-known member
Remember that tape manufacturers like BASF were chemical companies - pushing forwards with new formulations was their forte! Ampex were not a chemical company, so their tape components were bought in, making shortages a problem. BASF actually tried making equipment. By and large, it was pretty horrible, bar, one chunky cassette machine which I remember rather liking?
 

jamesperrett

Active member
Remember that tape manufacturers like BASF were chemical companies - pushing forwards with new formulations was their forte! Ampex were not a chemical company, so their tape components were bought in, making shortages a problem.
Yes, I don't think Ampex ever really got to the bottom of their sticky shed problems. Oddly enough, European made 3M (Scotch) tape like 256 never needs baking but American made 3M tape from the same era like 226 does need baking. And Agfa tapes that have never gone to the USA have always been fine but Agfa tapes from US studios have often given me problems. OK - so the last example may just be bad luck but it does seem to be more of a problem with US manufactured tapes.
 

RRuskin

Rick Ruskin
Yes, I don't think Ampex ever really got to the bottom of their sticky shed problems. Oddly enough, European made 3M (Scotch) tape like 256 never needs baking but American made 3M tape from the same era like 226 does need baking. And Agfa tapes that have never gone to the USA have always been fine but Agfa tapes from US studios have often given me problems. OK - so the last example may just be bad luck but it does seem to be more of a problem with US manufactured tapes.
Never heard about 3M 256. What were the specs? Was it also low noise/high output?
 

jamesperrett

Active member
Never heard about 3M 256. What were the specs? Was it also low noise/high output?
3M 256 was made at 3M's factory in South Wales and was initially formulated to conform to the BBC Type 200 spec which meant that tapes conforming to that spec from different manufacturers could be used on the BBC's machines without the need for re-alignment. Zonal 675 and (I believe) Agfa PEM468 also met that spec. It wasn't as high output as Ampex 456 but it had lower print through which was important for speech applications.

There's an interesting article on tape at the BBC at


and more discussion about 3M 256 at


With some recollections from people who used recorded with it.
 

TalismanRich

Well-known member
I've read several times that the problem with Sticky Shed is that the binder is hygroscopic, which means it attracts and/or reacts with water. Some of the comments are that this involves specific grades of polyurethane, which happens to be just such a material. Baking works by lowering the relative humidity in the over, at which point the urethane in the coating will release moisture until it reaches equilibrium with the surrounding atmosphere.

I would think that one would be able to prevent this by putting the reels in a very dry atmosphere. There are numerous dessicants, such as calcium sulfate and molecular sieves that will suck the water out of the air without releasing any problematic chemicals. Molecular sieves are really efficient at removing water, and can be easily regenerated and reused.

I wonder if anyone has tried this approach.
 

jamesperrett

Active member
I believe that it isn't just the take-up of water but also the break-up of the binder molecules into shorter chains. Baking restores the molecules back to longer chains.

However, I believe that Marie O'Connell in New Zealand has used a technique that involved freezing the tape.
 

halljack

New member
1975--1976 politics--REGULATIONS ---the OZONE ENVIRONMENTAL CRAP
THAT THEY WERE FORCED TO DO----ALL AMPEX TAPE STUCK
AFTER 1975. NOTICE JAPANESE TAPES TODAY ARE FINE--MAXELL--FUJI--ETC.
ITS ALL A HOAX
 
Top