| 摘要 |
<p>Materials, such as concrete or marble, are washed with a soln. contg. (NH4)HF2, then dried and treated with a water-repelling agent, pref. a soln. of an alkali siliconate, or a silicone resin with a solvent, or an emulsion of a silicone resin, or a successive combination thereof. The (NH4)HF2 soln. does not affect the limestone material.</p> |
