Breather material and method of coating fabric with silicone rubber

Sheet material for exerting substantially uniform pressure on a workpiece when a vacuum is applied between said material and said workpiece, comprising:

• a layer of breather material including a flexible fabric that has opposite major faces at least one of which is ribbed, and a plurality of holes extending therethrough between said faces, said holes being spaced over essentially the entire extent of said faces, and said fabric being stretchable in its general plane in at least two directions, with said directions being substantially perpendicular to each other;
• and a coating of silicone rubber release compound on said fabric covering at least the face opposite said ribbed face;
• said coating having a plurality of holes that extend therethrough and that generally coincide with said holes in the fabric, and any portions of said coating on said ribbed face substantially conforming to the configuration of said ribbed face, to provide passageways for a vacuum;
• and said release compound being flexible, stretchable, nonadherent to said workpiece, and not subject to damage or deterioration caused by contact with said workpiece;
• a layer of flexible, stretchable impervious material adjacent to said ribbed face;
• and
• adhesive between said impervious material and said ribbed face in an amount sufficient to firmly bond said ribbed face to said impervious material but insufficient to block said passageways.

A method of making foraminous sheet material having a ribbed major surface, said method comprising:

• laying a foraminous ribbed fabric on a horizontal surface of a material that will not adhere to silicone rubber release compound, and facing a ribbed major surface of said fabric upwardly;
• thinning liquid silicone rubber release compound with a volatile solvent in an amount sufficient to cause shrinkage of the compound of about 50% in volume upon drying of the compound;
• forming a puddle of the thinned compound that covers the fabric and is substantially flush with the top of the upwardly facing major surface of the fabric;
• and
• allowing the puddle of compound to dry to form a coating on the fabric, and allowing the compound to shrink as it dries to conform said coating to the ribbed configuration of the upwardly facing major surface and to allow holes through the coating to form where there are holes through the fabric.

A method of making flexible, stretchable sheet material having an impervious layer, a foraminous layer, and pasageways between said layers, said passageways communicating with holes in the foraminous layer and with edge portions of said material, said method comprising:

• laying a flexible, stretchable foraminous ribbed fabric on a horizontal surface of a material that will not adhere to silicone rubber release compound, and facing a ribbed major surface of said fabric upwardly;
• thinning liquid silicone rubber release compound with a volatile solvent in an amount sufficient to cause shrinkage of the compound of about 50% in volume upon drying of the compound;
• forming a puddle of the thinned compound that covers the fabric and is substantially flush with the top of the upwardly facing major surface of the fabric;
• allowing the puddle of compound to dry to form a coating on the fabric, and allowing the compound to shrink as it dries to conform said coating to the ribbed configuration of the upwardly facing major surface and to allow holes through the coating to form where there are holes through the fabric;
• and
• then bonding said ribbed major surface to a sheet of flexible, stretchable impervious material by applying an adhesive in an amount sufficient to create a firm bond but insufficient to block passageways formed by said ribbed configuration and said holes through the fabric and the coating.