Reading old tapes

From: Dennis Boone <drb_at_msu.edu>
Date: Thu Jun 24 19:20:07 2004

> The comment was that old tapes absorb moisture into the oxide, which
> makes things sticky and causes the oxide to stick to the wrong spots
> and flake off the tape. The solution is to set the tape in a fruit
> dryer at modest heat (150 F or so) for a while.

Libraries, archives, and other preservation organizations have been
dealing with this for some time. It's called "sticky shed syndrome",
and occurs when the binder layer absorbs water molecules. In some
cases, the tape will cause the tape to stick to the heads, pinch
rollers, etc, and even squeal loudly as it passes through the machine.
The problem doesn't just occur in tapes from the 80s.

Recipes vary quite a bit. Our library purchased a fancy small
convection oven for doing the work on a large collection of old audio
materials, but others use their kitchen appliances. Close temperature
control is important. One should be careful not to let things get
too hot, keeping in mind the hysteresis of the typical home oven.

Sticky shed often returns after a month or two; if you have tapes with
this problem it's best to copy the contents to other media promptly
after baking.

De
Received on Thu Jun 24 2004 - 19:20:07 BST