29 Aug
2015
29 Aug
'15
8:57 a.m.
On 8/28/15 9:25 AM, Jay Jaeger wrote:
Many/most 9 Track tapes (those from the early to
mid-eighties until 1995
or so - what matters is the date of manufacture, not when they were
written) have to be "baked" before reading, owing to "sticky shed
syndrome". My experience with tapes earlier than that is that I can
read them without baking them first.
Mid-80's are the worst, especially Memorex, and BASF, which everyone used
because they were cheap.
Whatever HP bought for their distribution tapes (probably Graham Magnetics) is very good.
IBM tape is good too.
DEC used crap tape for their distributions.
Sadly, AT&T and Mt XINU ALSO used especially bad tape in
the late 80's, so many of the Unix distributions I've been dealing with from
them lately are so sticky even after baking that they are impossible to deal
with.
If you are going to be processing a lot of tapes, get a portable "tape scraper"
(tape cleaner) and cover the blade. Retension the tapes with it at low speed
after baking. The shed on the cloth covering the blade will tell you how bad the
shed is. You can see a Graham Magentics portable cleaner in Paul's setup on the
right.
http://www.piercefuller.com/collect/proj.html
I've processed over a thousand tapes in the past ten years, and their condition
is not improving with time. Chuck has mentioned 3M Black Watch being bad, and I've
started to see that now too, which wasn't the case in the past.