I think that QRS experimented a few years back with using Mylar instead
of paper for music rolls. Apparently there were difficulties, probably
economic ones as well as such technical ones as Robbie mentioned,
because its use was not continued.
As Robbie said, the old green paper Wurlitzer used was very good,
stable, and longer lasting than most paper. I don't know a lot about
its manufacture. I was told by John Malone that he had it analyzed and
found a resin content in it. Visual inspection suggests it is the same
dry-waxed paper as is used today by roll manufacturers whose product is
intended for outdoor use.
One story has it that Wurlitzer imported the paper from Canada, but
most say it came from a plant in Erie(?), Pa. I have also heard that
it was the "gray music roll paper" used by Melville Clark's company,
but colored green [for Wurlitzer rolls].
Someone here on MMD actually has a couple of still-sealed drums of
original Wurlitzer green paper, and perhaps markings on it may show
something, but that is doubtful because Wurlitzer must have had to cut
down the long rolls of paper as they came from the paper mill. Whereas
some perforators (including those at Play-Rite and QRS) trim the paper
as it goes through the perforator, Wurlitzer's paper was cut to exact
size before perforating. The Herschell Carrousel Factory Museum still
has one of the Wurlitzer paper slitters.
None of the above is particularly trustworthy, but is just thrown out
here prompted by Robbie's comment on Jeff Alterman's Mylar idea.