[ Tony Pignaloni wrote in 080816 MMDigest:

> The rubber bands had just enough tension that the boards
> weren't clamped tightly shut -- just tight enough.

While clamping the pneumatic (by whatever method), place a small
block of felt between the boards at the opposite end from the hinge.
This will hold the pneumatic slightly open while being clamped and
not cause the cloth to be creased. A sharp, pressed crease will
deteriorate (develop pin holes) faster than the rest of the cloth.

Regards,
Jon Page