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: An alumina porous body which comprises coarse alumina particles as a filler and SiO.sub.2, said alumina and SiO.sub.2 forming an Al.sub.2 O.sub.3 -SiO.sub.2 compound (mullite) on the surface of the coarse alumina particles through the reaction between them that takes place at the time of firing, said compound binding said coarse alumina particles, forming pores between them. The invention also relates to a process for producing an alumina porous body which comprises mixing coarse alumina particles with SiO.sub.2, molding the mixture, and firing the molding at a temperature not higher than 1700.degree. C., thereby sintering the coarse alumina particles.