Method of manufacturing an object of a powdered material by isostatic pressing

A method of manufacturing an object of a powdered material by isostatic pressing of a body, preformed from the powdered material, with a pressure medium, whereby the preformed body, in which at least the surface layer consists of a ceramic material in the form of a nitride, is surrounded by a boron oxide-containing casing which is made impenetrable to the pressure medium, before the isostatic pressing is carried out while sintering the powder, wherein for the material in the casing there is used boron oxide, or a glass containing boron oxide or a material containing boron oxide which forms glass upon heating and in which the content of boron oxide is at least 30% by weight such that the glass, or the glass formed upon heating, is removable by water, that the preformed body surrounded by a casing is subjected to a heat treatment for the formation of boron nitride on the surface of the preformed body and the boron oxide in the casing, before the isostatic pressing is carried out, and that at least that part of the casing which is located nearest the manufactured object is removed by water or water vapour.