| 摘要 |
<p>A water resistant plaster composition comprises a dry mixture of gypsum, a water soluble cellulose derivative and a small amount, preferably not more than 5% by weight of methyl sodium siliconate or methyl potassium siliconate. Up to 5% of wood flour or asbestos flour or floats and about 1% of a retarder such as borax or sodium carbonate may also be added. The cellulose derivative such as methyl cellulose, carboxy methyl cellulose, ethyl methyl cellulose, oxy-ethyl-methyl cellulose or hydroxy ethyl cellulose or mixtures of these forms 0,25% to 6% by weight of the composition and the siliconate is added to the plaster either as a dry powder or as a solution in a solvent which does not react with the plaster.</p> |
