When recovering pneumatics I like to have the pneumatic closed when
I glue the cloth across the hinge end.  I found a good way to keep
note pneumatics lightly closed by using a gentle clamp.

Take a length of 3/4-inch (19 mm) diameter automobile heater hose and
cut it in lengths of about 3/8-inch (9.5 mm) long so you have a bunch
of circles.  Cut through one side of the circle, sort of like a "Q"
with the tail being the cut.

Close the pneumatic, open the hose ring, and put the hose across the
pneumatic leaves like a "C" shaped spring clamp.  This holds the
pneumatic closed but does not put the "Godzilla crunch" on it.

John Dewey
Penfield, Illinois