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Sorry,
I was quoting from memory and not the 3M product sheets.

Thanks for the correction.

Corey

At 03:46 AM 12/18/2009, you wrote:
>Corey:
>
>This history is wrong about Scotch formulations.
>
>Scotch released 206, 207 and 208 in the late 1960's. Around the same 
>time, Ampex released the original formula of 406 and 407. I can tell 
>you for a fact that 206, 207 and 208 (which was designed for low 
>print-through and low noise for sound-for-picture work) were around 
>before 1970, I have reels dated 1968 and 1969.
>
>As I understand the sticky-shed story, at some point in the 1970s, I 
>think the early 1970s, Ampex changed some ingredient in their binder 
>"stew" and this was the root cause of the problem. It effect 406/407 
>from that point onward and also effected the later Grand Master 
>456/457 line. Richard or someone else can say for fact whether it 
>effected more advance Ampex formulations like GP9. At 3M, the 
>chemistry was not changed for 206/207/208 but the new 226/227 that 
>was introduced in the late 70's or early 80's had the same 
>sticky-shed problems as Ampex tapes. Also 250, I think. Also the 
>formula that 3M came out with for Nagra location-sound recorders, I think.
>
>After the sticky-shed problem was discovered and baking was deemed a 
>suitable solution to play a sticky tape, Quantegy (the former Ampex 
>tape division) supposedly changed the formula of all their 
>back-coated tapes to prevent sticky-shed. There are varying reports 
>whether this is true. I have 406, 456 and 457 stock from as far back 
>as 1998-99 timeframe that has not gotten sticky so far, but others 
>report other results. 3M exited the tape business in the 1990's, so 
>their formulations with problems were never changed.
>
>Somewhere online used to be an annotated history of 3M formulations.
>
>-- Tom Fine
>
>
>----- Original Message ----- From: "Corey Bailey" <[log in to unmask]>
>To: <[log in to unmask]>
>Sent: Friday, December 18, 2009 1:40 AM
>Subject: Re: [ARSCLIST] Tape Squeal
>
>
>>Hi Shai,
>>
>>Scotch 206 was 1.5 mil polyester, back coated and the top of the 3M 
>>line until
>>the introduction of 250. 207 was the 1 mil version of 206 and, as far as I
>>know, was the same formulation. During the 80's, 3M released Scotch 
>>208, aimed
>>for the feature film production sound community claiming it was as 
>>reliable as
>>206. I till have some 208 from that era. I should check it out.
>>
>>"If it ain't Scotch 206, Bake it!" was somewhat of a 
>>tongue-in-cheek statement.
>>However, of all the formulations that were produced, 206 seems to 
>>have been the
>>most stable over the years. This doesn't mean that it should not or cannot be
>>baked, but I am comfortable with playing it before making that decision.
>>
>>Cheers!
>>
>>Corey Bailey
>>Corey Bailey Audio Engineering
>>
>>
>>Quoting Shai Drori <[log in to unmask]>:
>>
>>>Please continue this discussion on list. I have also found that baking
>>>most tapes helps them run on the machine. Don't have much experience
>>>with 206 so I must ask why should this be excluded? Is it the standard
>>>length version of the 207. I had a couple of these that were back
>>>coated. The emulsion just came off the tape one day. I tried Last's
>>>product for vinyl and was very disappointed. What product did you use?
>>>Maybe different products produce different results.  I'm still waiting
>>>to see photos from Marie's mods.
>>>Shai