Abstract: Jeans are bleached by rotating glass-expandable ceramics having a bulk specific gravity of 0.7 to 1.2, a 24 hour water absorption of not greater than 5% and the maximum diameter of not greater than 150 mm, water and jeans in a rotary tank. Further jeans are bleached by rotating an air-permeable ceramic porous material having a bulk specific gravity of 0.7 to 1.9, a 24 hour water absorption of 10 to 40% and the maximum diameter of not greater than 150 mm, water and jeans in a rotary tank. In this case, the air-permeable ceramic porous material may also be immersed in a bleaching agent solution.

Abstract: A thermally insulating foam glass tile includes a tile-like body consisting essentially of a vitrifiable mineral and having a substantially closed cell structure, and a rigid reinforcing vitrified surface skin permeated into at least the top surface of the tile-like body. An intermediate vitrified layer having a lesser volume of closed cells may be integrally melt-bonded between the tile-like body and the surface skin.

Abstract: A method for producing a foam glass tile having a surface skin comprises the steps of molding a material consisting essentially of a vitrifiable mineral and a foaming agent into a tile-like block; coating the block with a thin layer comprising a vitrifying agent for the mineral material; heating the coated block to a temperature sufficient to fuse the coated layer whereby the molten vitrifying agent permeates into the coated surface of the block; and further heating the coated block to a temperature sufficient to soften the vitrifiable mineral. The method may further include the step of forming a thin layer comprising a vitrifiable mineral and a lesser amount of a foaming agent between the tile-like block and the vitrifying agent layer, followed by firing. The foam glass tile formed by the above method comprises a foam glass tile body and a rigid reinforcing vitrified surface skin, the surface skin being integrally melt-bonded onto at least a top surface of the foam glass body.