To provide a technical method for preparing a multipurpose base material which can be produced by only altering a firing temperature and a firing time using the preparation of the base material with a common raw material when the preparation of the base material which can produce a lighter ceramic by a low temperature firing is developed and when an energy saving or an ecological product such as a ceramic for shielding external heat, a breathing ceramic for adsorbing a polluted gas in a room and the like is developed corresponding to the demands of the present age.

The raw materials to be melted such as feldspar and the like being used for the preparation of the base material are replaced by materials to be melted such as waste glass and the like. Silica and the like are replaced by porous lightweight materials such as kieselguhr and the like. If desired, the preparation of the base material using porous lightweight plastic materials such as sepiolite and the like is developed. The mineral amount in a ternary rational formula is calculated at every preparation and then the sintering temperature at developing preparation is estimated by a triangular diagram for presuming the landing softening temperature of a Seger cone (SK). The lightweight ceramic fired at a low temperature is obtained by using the developing preparation whose sintering width is stabilized. The ceramic for shielding external heat, the breathing ceramic for adsorbing the polluted gas in a room are produced without changing a sintering furnace and facilities, as it were, the preparation of the base material easy to be in the common use of three kinds is obtained.