Why would heavier leather fail
before the more delicate leather?
Pipe Organs produce their sound by means of compressed air supplied by the blower. The compressed air used by the pipes is also used to make the action function. The dynamic force of the wind is capable of lifting the tops of the various reservoirs even with several hundred pound of spring tension and lead weights placed there to regulate the windpressure.
Inside the windchest, equal windpressure is applied both inside and outside the pouches and are thus said to be “balanced” actions. However the exposed leather on the reservoirs have pressure applied to only one side (the “back” side) and have to withstand the constant pressure of the wind inside the reservoir.
Common Household Dust (left) and Pollen (right) are shown here, greatly magnified. Now— imagine these particles propelled at high speed through a small hole or tear in the leather. These particles destroy the leather from the inside out.