yes, I developed a radar absorbing coating , which can simply be applied on nearly every surface. It is very tough (passable) and reduces radar reflections between 5 and >110 GHz by 99 ... 99,99 %. [mailto:arrow33@gmx.de arrow33@gmx.de]

yes.glass wool is one of the sound absorbing material while ground glass is not.

wikipedia says

One of the most commonly known types of radar absorbing material is iron ball paint. It contains tiny spheres coated with carbonyl iron or ferrite. Radar waves induce molecular oscillations from the alternating magnetic field in this paint, which leads to conversion of the radar energy into heat. The heat is then transferred to the aircraft and dissipated. The iron particles in the paint are obtained by decomposition of iron pentacarbonyl and may contain traces of carbon, oxygen and nitrogen. Carbonyl iron is also used as a catalyst and in medicine as an iron supplement, even though it is toxic in higher doses.

Yes

Its absorbing the water.