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What the NPC is Not Telling You

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With a lot of publicity and fanfare, the National Plasterers Council (NPC) recently invited the onBalance group to participate in new test pool studies to determine the cause of plaster spotting, which they claim is caused by aggressive pool water.

The NPC wants the test pools plastered with good workmanship and supervised by onBalance, and then they want the pool water to be maintained aggressive (per LSI) to see if spotting develops on the plaster surface.  The NPC says “the testing could take months or even years to bear results.”

Interestingly, this proposal comes on the heels of the NPC spending about a million dollars of industry money at Cal Poly (NPIRC) for test pool studies over a period of years.  Didn’t they learn about proper and improper workmanship practices and aggressive water during those studies?  So what happened at Cal Poly?  Well, that is just part of many things the NPC is NOT telling the industry.

The NPC says that they don’t want to debate this issue. That indicates that they do not want to address the actual Cal Poly test pool results, and the findings by several prominent cement labs on spotting.  It appears that the NPC does not want this information made available to industry professionals and cement/plaster experts to review and evaluate.

There are a number of things that the NPC leadership has not publicly acknowledged, even to their own members.

1. Starting in 1999, and through 2003, two professional cement scientists, who are experienced in forensic analysis to determine the cause of cement (plaster) problems, began to identify specific improper workmanship practices as leading to the plaster spotting problem.  The NPC has never addressed those lab findings.

2. In 2004, the two Cal Poly professors concluded in Phase 1 that aggressive water causes “spot etching.” Yet, in a 2005 report to the International Cement Microscopy Association (ICMA), the same two Cal Poly professors contradicted that Phase 1 conclusion by stating that they did not determine the specific causes, whether chemical or workmanship, of plaster spotting.  They also changed the term and defined the spotting problem as “spot alteration” instead of “spot etching.”  The ICMA report mentions that the spots were soft, had micro-cracking, and also mentions improper workmanship issues as possible causes of the spot alteration phenomenon.

3. The Cal Poly (2004-2005) Phase 2 report concluded that aggressive water has the most profound effect on the “etching deterioration” of pool plaster,” which of course, is true.  However, no conclusion was made in regards to spot etching / spot alteration. The same for Phase 3 and 4.

4. The data within the Phase 2 report indicate that 4 test pools resulted in spotting, yet the water was balanced or had positive LSI water in those pools over an eight month period, which would indicate poor workmanship was involved.  Several other balanced water test pools did not spot, which would indicate good workmanship was performed on those test pools.

5. The data within the Phase 3 & 4 reports indicate that some tests pools had aggressive water about one-half of the time (eight months) and did NOT spot or have any discoloration.  This also would indicate good workmanship was performed in those test pools.  The NPC has not acknowledged this revealing evidence to the industry.

6. In 2012, four prominent cement labs with their scientists (using petrographic analysis) determined similar findings (poor workmanship) on the cause of spotting, and describe the spots as white, soft, porous, and with an abundance of micro-cracks. Why hasn’t the NPC acknowledged and addressed these lab findings?

7. The cement labs did not find evidence of LSI aggressive water as contributing to the spotting problem.  (Of course, LSI balanced water could be defined as being “aggressive” towards the soluble cement compound known as calcium hydroxide, and would dissolve it away from a plaster surface. That process is known as “leaching” which is a term the scientists used in their reports).

8. While the issue and cause of spot alteration is complicated, that is not the only plaster problem that plasterers and NPC inspectors are blaming on water chemistry.  Would you believe that some plasterers are not accepting responsibility for bond failures (delaminations), plaster cracking, gray mottling discoloration, calcium nodules, and spalling (flaking)? According to some NPC consultants and advisors, bad water chemistry causes those problems too.

9. Yes, NPC consultants and inspectors are helping poor quality plasterers get away with bad workmanship. This certainly doesn’t help the quality pool plasterers out there.  It appears that when a plaster job goes bad, the plasterer tries to convince the pool owner that it is a water chemistry problem. Sometimes that doesn’t work, and he calls out an NPC plaster inspector, who convinces the innocent and uniformed pool owner (or service tech in some cases) that all of the available science has proven that aggressive or bad water chemistry causes the above plaster problems (defects).

10. In 2003, the NPC announced that they would not debate anyone about the information contained in their NPC Technical Manual, or about spotting and other plaster defects.  We had information that the NPC Tech manual contradicted literature from the ACI and PCA.

11. A few years ago, the NPC declined a media outlet (Pool Genius Network) invitation for a debate with onBalance in regards to gray mottling discoloration.

12.  In 2011, onBalance extended an invitation to the NPC to participate in a study on a white spotted pool, where plaster samples would be taken and sent to various cement labs for forensic analysis.  The NPC declined.

It appears that the NPC doesn’t want to quickly resolve any of the various plaster defect controversies, which a moderated discussion and sharing of previous test pool studies and science material would do.  The poor quality plasterers and NPC inspectors benefit the most to keep things unresolved because they have the advantage at poolside with uninformed pool owners. 

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Comment by Kim Skinner on November 6, 2014 at 8:37am

Richard, the NPC leaders are not only rejecting the cement lab forensic findings on spotting, but also are ignoring (rejecting) their own test pool study results done at Cal Poly. We accept both of those findings and are not "skeptical" of them. They both prove that improper workmanship is what causes spotting. The NPC is also ignoring other past (1990's) test pool experiments and results that they were involved in.

The NPC constructed 12 pools and two spas at Cal Poly and ran experiments on them for four years. The actual results of those test pools proved that aggressive water doesn't cause spotting. The NPC are now ignoring those results because they aren't the results that they were hoping for.

So now they want to do more test pools. But their suggested protocol is flawed and will cause mixed results, and still leave things unresolved. They want to do color pigmented plaster, which we all know is problematic. 

Their proposal will only delay a resolution and will only help the NPC inspectors continue to mislead pool owners. There is no point in doing more test pools; the NPC will be skeptical again if they don't prove what they want. It is also another delay tactic, and to avoid addressing what has already been proven. 

When the NPC leaders finally acknowledge the above and put a stop to plasterers and their inspectors blaming water chemistry for known plaster defects such as, calcium nodules, craze cracking, gray mottling discoloration, and also white soft spotting, then we move forward and look at further research studies for the common good of the industry. 

Comment by Richard A. Falk on November 5, 2014 at 9:24pm

I think that both approaches should be taken -- a review and debate of the previous studies as well as field or laboratory tests under the supervision/observation of both.  Both sides will be skeptical of studies done in the past by the other so even after debating such studies there may still be lingering doubts only squelched by specific experiments.

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