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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
>>
>