Surface Preparation第 6 / 100 题
What causes efflorescence, the white crystalline deposit sometimes seen on masonry and concrete?
a.Excess paint sheen reacting with sunlight
b.Water carrying soluble salts to the surface, where the water evaporates and leaves salt behind
c.Sanding dust left on the wall
d.Overheating of latex paint during curing
解析
Efflorescence is water-soluble salt that migrates through masonry as moisture moves to the surface and evaporates. Painting over it traps salt and moisture, causing the coating to peel. The deposit must be removed (dry brushing or a masonry cleaner) and the moisture source addressed before coating.
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