Perforated mat for generating air bubbles

摘要

A bed of nails is pressed into a sheet of elastic or semi-elastic material which is supported on a layer of felt in order to manufacture the mat. The material used can be polyvinyl chloride, rubber, leather, metal, glass fibre and some ceramics. The nails make microscopic tears in the material. The material round the holes partly springs back when the nails are removed. When the holes in the sheet are subjected to air pressure, the holes open up again to a degree depending on the air pressure.