Abstract: A process for the mechanical treatment of porous sheet materials entails introducing a particulate material into the pores of the sheet material to block the pores, carrying out the mechanical treatment, and then removing the particles from the pores. The process enables porous sheet materials to be subjected to mechanical operations, for example shaping under gaseous pressure or surface polishing, which could otherwise only be applied to non-porous materials.

Abstract: This invention relates to a porous panel for use principally, but not exclusively, for the distribution of a freezing point depressant liquid on an aircraft surface in order to provide protection against atmospheric icing. The panel comprises an outer porous sheet over the surface of which the fluid is to be distributed, a backing sheet of microporous material in contact with one side of the outer sheet, and a sheet of fluid impervious material which is spaced from the microporous sheet. The sheets may be secured to one another by adhesive bonding over a region located outwardly of the space. The outer sheet may be a porous material, a reinforced porous plastic material or a drilled sheet material.