To make it possible to assure a sufficient time before gypsum cures and to easily carry out the work for finishing the gypsum by adding a curing retarding material which is fine in particles and has a high water holding rate to the gypsum, then mixing the gypsum and water and retarding a moisture supplying rate to the gypsum by this curing retarding material.
The curing retarding material which is preferably barium sulfate powder of the fine particles, for example, about 150 μm in the max. grain size having the high water holding rate is added to the gypsum (for example, anhydrous gypsum) at a ratio of, for example, 1:3 by weight and thereafter, the water is added to the gypsum at a ratio of, for example, 1:1 by weight, following which the mixture is mixed. When the front surface (free surface) of the gypsum is finished smooth by pouring the mixture into a form or when the mixture is finished to an intricate shape without the form, the curing rate of the gypsum is made lower than in the case the curing retarding material is not used and therefore, the sufficient time may be taken for the finishing work and the work is made easier.
Tsuchida, Yasuyoshi
Moriyama, Satoshi
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