Non-baking cure for sticky shed? (being serious for a moment)

Jon Elson elson at
Mon Jan 18 11:46:21 CST 2016

On 01/18/2016 10:56 AM, js at wrote:
> Interesting.  I just happen to have a 3M Black Watch tape 
> right here next to me that I'm using to test a Mark 300 
> tape cleaning machine.   The tape so far is fine, not 
> shedding anything front or back.
Sorry about previous reply, hit wrong button.

Well, I don't know if it was the Black Watch that was the 
problem, or somebody else's version.
We started with spring-arm drives, which could not keep 
constant tension on the tape.  You'd hear this HORRIBLE 
scrunch noise at various times when the tape was being 
processed, which was the layers of tape sliding over each 
other.  Usually didn't cause problems, but on occasion it 
could be so bad that the drive would lose tension and shut 
down in the middle of the reel.

Vacuum column drives didn't seem to have much of this 
problem.  I think it was the jerk of tension when the drive 
reversed to reread a bad block that started the slipping on 
the spring arm drives.

Longevity of tapes was very spotty.  Some expensive, 
name-brand tapes just disintegrated after a few years.  
Others have held up amazingly well.  Last year I read in 
some 1993 backups of my MicroVAX system with no trouble at 
all.  I did have to clean the tape head after every tape, 
but that wasn't greatly different from when the tapes were new.


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