Hémihydrate

The formula of the hémihydrate of the Sulfate of calcium is CaSO4, 1/2 H2O. There are 2 varieties:

  • the alpha variety, obtained by pressure-sealing of pulps of Gypsum to 120°C intended for the Plaster of moulding and to certain uses requiring a harder material (2,76 g/cm ³)
  • the beta variety, obtained by cooking out of furnace with 150°C, intended for the more traditional uses of the Plaster (2,63 g/cm ³)
The manufacture of the first, under certain conditions, is cheaper than that of the second, when one applies it to the Phosphogypse.

Random links:Jean de Brunhoff | Friaize | Government (Spain) | Zapping generation | Rupert Sheldrake | Premiers_magistrats_de_Michael