Thanks, John. I never really understood that.

Best,
John

On Sun, Jan 24, 2016 at 2:05 PM, John Chester <[log in to unmask]> wrote:

> On 1/24/16 1:33 PM, John Haley wrote:
>
>> I have followed this long thread but frankly have found a lot of it
>> confusing. David, I have always assumed it is in fact the black
>> back-coating that is what has turned sticky and gums up the machine on
>> unbaked tapes. It wouldn't be the oxide layer coming off like that.
>>
>
> In my experience, which is mostly with Ampex tape, both the oxide and the
> backcoating are sticky, and some of the oxide is coming off when an unbaked
> tape is played. The deposit that forms on heads and guides exposed to the
> oxide side of the tape is mostly oxide, although initially it seems to be
> somewhat darker in color than the oxide. I think some of the backcoating
> becomes embedded in the oxide.
>
> In the worst case, large chunks of oxide are so solidly attached to the
> backcoating that they are pulled off the base. (But I've never seen large
> chunks of backcoating pulled off the base.....)
>
> The deposit that forms on static surfaces exposed to the back of the tape
> is mostly backcoating.
>
> -- John Chester
>