Andy Taylor wondered about reducing roll friction against the tracker
bar.  20+ years ago good old PPC sold a spray-can lubricant for this
purpose.  Unlike silicone sprays, it dried hard and was supposed to last
for a while.  I used it on my Duo-Art with no ill effects, though I can't
swear that it helped either.  (Art Reblitz' book credits Duo-Arts with
large, powerful wind motors).

I can understand that if a roll has been playing for a while at low
volume, so that lots of it is wound on the takeup spool rather loosely,
and an increase in vacuum (or a momentary snag in the supply spool)
suddenly increases the drag on the roll, then the paper will slip on the
takeup spool (the way it does when you tighten a re-rolled roll by hand)
and the music will falter.

That spray coating would help prevent this.

BTW, most of the brass plating is worn off my tracker bar, exposing the
darker cobber (bronze?) beneath.  That may affect the friction drag on
the roll.

I doubt that bleed size makes any difference.  When a tracker hole is
closed, it should go to full stack vacuum regardless of bleed size or
pouch porosity, unless the roll paper is terribly porous.

Unfortunately, PPC also claimed this spray was great for lubricating
knife-valve surfaces in tempo and expression regulators, in lieu of
graphite rubbed in.  I found it worked great for a while, but in the long
run the coating probably wears off and the two wooden surfaces start
chewing each other up.

Lacquering the tracker bar sounds like a recipe for trouble; I'm still
looking for the joker who spray-painted my organ barrel: pins, staples,
and all !   :-)

Mike Knudsen

 [ I used a Teflon coating process called "Microseal" on the stationary
 [ guides in a large mag-tape drive.  It certainly reduces sliding
 [ friction, but, because most paper is quite abrasive, I don't know
 [ how long it would last as a tracker-bar coating.  -- Robbie