Some plasterers are occasionally finishing pools so fast that it detrimentally affects the quality and durability of plaster surfaces, and are not even aware of the consequences. And the NPC is enabling for this to happen. This needs to stop. Improper practices can speed up the finishing process, but they also lead to a short life-span for plaster, lasting only five-ten years instead of twenty. They are not doing the consuming public right by condoning, and by omission endorsing, those improper practices.
Even worse, combining improper practices to the point of being excessive can lead to plaster defects, deteriorations, and discolorations showing up on plaster surfaces (including quartz and pebble) within a couple of weeks to one year of time.
Last year, NPC board members assisted in writing and approving an ANSI Plaster Standard that did not include specifications, limits, or warnings about the amount of water being added, calcium chloride content, excessive wet troweling or late hard troweling. That is irresponsible. Are there no such things as improper workmanship practices that cause early deteriorations? Is it the purpose of this document to protect plasterers from being held responsible for causing defects and discolorations?
Yet, back in 1998, NPC acknowledged (in their Technical manual) that improper practices cause calcium nodules, spalling (flaking), severe craze cracking, and hydration (graying) of white plaster.
But that changed in 2002 when new NPC leadership took over wrote a new Technical manual. The correct information on the causes of the above plaster defects were removed, and now NPC literature and consultants suggest that “aggressive water” causes those defects.
Essentially it is being suggested that if pool water has an alkalinity of 70 ppm or an LSI of just -0.1, then that is deemed as “out-of-balance” or “aggressive water” and causes plaster defects. That would be wrong, and there is no factual basis to claim that; but blaming service techs and pool owners for these problems happens often.
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 as the causes.
In 2003, IPSSA and others wrote to the NPC requesting the supporting documentation for the changed positions on those plaster problems. The NPC responded that they would not provide any evidence for the new Tech Manual changes, and that there would be no further discussion or debate.
The NPC then decided to conduct test pool studies at Cal Poly/NPIRC to try and prove their theories. But just like their similar studies conducted during the 1990’s, the results didn’t turn out the way they had hoped.
The 2004-2007 test pool studies showed that aggressive water did not cause the above plaster defects, including ”spot etching” (white soft spotting), which indicated improper practices was the likely culprit. But the NPC did not acknowledge that and misled our industry on what happened at Cal Poly. Now the NPC wants to do even more test pools instead of admitting to and abiding by those documented results.
It is readily apparent why the NPC refuses to sit down with anyone and discuss the Cal Poly results, and no longer sell the four full (100+ page) reports (Phases 1, 2, 3, & 4) from Cal Poly/NPIRC.
The NPC should be acknowledging what has been proven by their own Cal Poly/NPIRC studies (and documented by an independent peer-review), and the science and findings by professional cement authorities (who are experts in forensic analysis) that have identified improper practices that lead to early deterioration, discoloration, and plaster/cement defects.
The NPC should be promoting quality workmanship and start teaching their members the correct information about proper and improper plastering practices at their yearly conferences and in their Technical Manual. Until then, poor workmanship will result and be empowered, and uninformed service techs and pool owners will continue to be misled and victimized when plaster problems occur.
Sadly, our industry is letting (and in some cases, helping) the NPC get away with this agenda.
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