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Are NPC leaders really trying to resolve plaster problems, or will they continue to ignore and/or misrepresent the research studies that have already provided the answers? The NPC says that there has been decades of debate regarding plaster problems. Actually, there have been decades of pool plaster studies, but no honest discussions or debates, and no accountability.

There was a time when NPC leaders understood that improper plaster workmanship can cause plaster defects and discolorations. In fact, the 1998 NPC Technical Manual acknowledged that delaminations, calcium nodules, cracking, flaking, and graying (mottling) of white plaster were due to improper workmanship practices (which is consistent with ACI and PCA literature).

But that changed in 2002 when a new NPC Technical manual was written. The correct information on the causes of the above plaster defects was removed, and now states that aggressive water causes those plaster defects, including white spotting. The NPC made those changes without any new supporting evidence.

Let’s note that the American Concrete Institute (ACI) and Portland Cement Association (PCA) do not blame rain water (which is significantly aggressive) for causing the above defects on cement surfaces. Instead, they cite improper workmanship and/or material additives issues as causes.

In 2003, the IPSSA organization and other groups wrote to the NPC requesting the supporting documentation for the changed positions on those plaster problems, and information that contradicted ACI and PCA guidelines on workmanship practices. The NPC responded that they would not provide any evidence for the new Manual changes, and that there would be no further discussion or debate.

The NPC then decided to conduct test pool studies at Cal Poly to try to prove their theories. But just like the studies conducted during the 1990’s, the results didn’t turn out the way the NPC had hoped. Now the NPC wants to do even more test pools instead of abiding by their own studies’ results, and even though they have already conducted “aggressive water” test pool experiments at Cal Poly.

The reality is that those study results showed that aggressive water did not cause white spotting (spot etching), or cause the other above plaster defects when proper workmanship was performed. Also, some of the balanced water pools did result in white spotting, which indicates poor workmanship was the likely involved. The NPC has been silent about those results.

Also, the NPC also participated in a separate study and learned that the Bicarb Start-up program was superior to the Traditional Start-up for the protection of new plaster, yet they don’t recommend it.

It is obvious that the NPC leaders don’t want the Cal Poly research results scrutinized and revealed, and don’t want to acknowledge the findings by four prominent cement labs (who specialize in forensic analysis) that identified improper workmanship practices as causing white spots, and that aggressive water chemistry was not the cause.

The time for test pool studies is over. The NPC should step up and accept the truth and reality of what has been proven by every study conducted. They need to accept responsibility for plaster defects that are caused by poor workmanship practices. Until then, uninformed pool owners and service techs are continuing to be misled and victimized.

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Comment by Kim Skinner on December 8, 2014 at 5:06pm

The NPC is now claiming that their Technical Manual has been peer reviewed by the pool industry.  As my post states above, the NPC turned down requests for data and supporting evidence years ago, and refused to discuss the matter any further.

Furthermore, there is a critique by a PhD cement petrographer that points out serious problems with some of the text that is contained in their Technical Manual. Will they ever address that?  

The NPC is also claiming that all plaster pools have defects, and nothing can be done about that.

If we just didn't have to fill the pool with water, then nothing would go wrong. 

Quality plaster and workmanship just doesn't seem to matter to some. 

And just to clarify to those who think otherwise; bad water chemistry does cause problems. Aggressive pool water will cause uniform etching, too high of a pH, alkalinity, and calcium levels (over saturated) will causes calcium scaling problems, and metals in the pool water will stain the plaster.  

Comment by Kim Skinner on December 5, 2014 at 2:25pm

I need to add that some of the test pools at the Cal Poly center had balanced water the entire time, and yet developed some severe craze cracking, and some had gray discoloration in different areas of the test pools. That should be good evidence that those plaster problems are not due to bad water chemistry as some NPC people have been claiming.  And of course, the ACI and PCA have cited poor workmanship and materials as contributing to those kind of problems, not aggressive water.

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