Other Plaster Discoloration Issues

The first picture shows white streaking on dark colored plaster caused by excessive and inappropriate water troweling, and the addition of calcium chloride to color pigmented plaster. In time, the color pigment is dissolved and lost from the plaster finish due to the porosity caused by the above issues. This shows that “white streaking” can sometimes occur as opposed to “white spotting.”

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The second picture shows white soft and porous areas on the floor of a white plaster pool.  The pool plasterer had sprayed down the new finish with water before filling (because some leaves blew in), which should never be done.

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The third picture is of the top step of the same pool.  Note the upper right corner has small white soft spots.  That area of the step is slightly lower than the surrounding step area, and the water collected  (puddled) there after being sprayed down. I believe this area was also negatively affected by being submerged in water too soon after finishing.

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The white porous areas in this pool did not begin to appear until about two months after completion.  This particular pool was filled with hard well water, and never had aggressive water. How do I know that? It was my personal pool built twenty years ago. 

A cement lab determined that the pool plaster contained an excessive amount of calcium chloride (3.5%), the surface had not been etched by aggressive water, the white areas were soft and porous, and had simply degraded over time. 

Because these types of discoloration problems don’t become visible immediately after plastering, some industry members believe that “imbalanced” water chemistry has to be the cause.  It needs to be understood that aggressive water doesn’t cause white discoloration. 

Instead, improper water-spraying new pool plaster, filling too soon, adding too much calcium chloride, and water troweling, can eventually lead to “white discoloration” (porosity) issues on new white or dark colored pool plaster, including quartz. 

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