  Previous statistical studies on the mechanical properties of
chemical-vapor-deposited (CVD) suspended graphene membranes have been performed
by means of measuring individual devices or with techniques that affect the
material. Here, we present a colorimetry technique as a parallel, non-invasive,
and affordable way of characterizing suspended graphene devices. We exploit
Newton rings interference patterns to study the deformation of a double-layer
graphene drum 13.2 micrometer in diameter when a pressure step is applied. By
studying the time evolution of the deformation, we find that filling the drum
cavity with air is 2-5 times slower than when it is purged.
