Heavy cheese cloth, light and heavy duck, ticking.  They all are
original.  I go to the fabric store and look for cotton duck, ticking,
canvas, or whatever that store calls it.

I have 4-5 different thicknesses and grades that I use for hinges.
There are that many thicknesses used in various player systems.  They
are all unbleached ivory color like the original.  Sometimes it is
striped for pillows or featherbeds.

The heavy duty canvas is used for bellows, feeders, reservoirs--also
for reed organ bellows.  The thinnest is used for pneumatics.  It is
slightly thicker than a muslin sheet and is called unbleached muslin.
Even the striker pneumatics that never had hinges get them in my shop
but I use the thinnest grade of hinge cloth.  Some striker hinges used
a thicker cloth.  I put back what they had, as a rule.

It is good to have several varieties of hinge material so you can
examine whatever you find inside the original and select an exact
replacement.