RE: [AV Media Matters] arsclist RE:Re-evaluating Tape

[Peter Brothers <lists@specsbros.com>]

Stock for Mastering

On June 7, Graeme wrote:

"I can't recall ever having seen a case of backcoat failure from any
of the manufacturers."

Probably the worst case of backcoat failure was on the Fuji 1" H-621 video
tape.  The stock frequently had backcoat related stiction problems and we
have not seen a reel of H-621 over 10 years old that did not have massive
backcoat shedding.  The stock was replaced with H-621 E that does not
exhibit the same problems.

Debris testing at our facility often shows as much or more shedding of
backcoat material than material from the recording surface on many tapes,
both audio and video.  Luckily, most backcoat shedding is "dry"
shedding and
can be removed with a simple cleaning.  As Jim Wheeler indicated, however,
oligomer residue can be produced by or "bloom" through the backcoat.

In general, even though backcoat decay is a problem we encounter
on a daily
basis, it is not a problem we have had particular difficulties
dealing with
or correcting during restoration processing.  It is possible that Jim
Lindner's disenchantment with backcoating resulted from a run in with a
batch of the aforementioned H-621.  It should also be noted that backcoat
shedding can and does contaminate the recording surface of adjacent tape
wraps.  This seems to be more of a problem on video than audio tapes.

Peter Brothers
President
SPECS BROS., LLC
peter@specsbros.com
web-site: http://www.specsbros.com
TAPE RESTORATION AND DISASTER RECOVERY
SINCE 1983