Look at the fan laws. that will help you use pressure to calculate flow.
I would measure flow of the compressed air,
let the compressed air enter a chamber
the chamber would have one end open with the cloth to be tested
increase pressure to some level. measure the flow into the chamber.
change your cloth, increase pressure to that same level. measure the flow.
if you know the flow into the chamber and the resistance, or pressure drop across the cloth, you can determine the resistance.