The NPC has drafted a plastering standard which has been submitted to ANSI for approval. But the NPC did not include and address many proper and improper workmanship practices, such as, limiting water content (water-to-cement ratio), calcium chloride additions, and wet (water) troweling. These are all very important issues for the making of quality pool plaster.
And unfortunately, an article by Pool & Spa News about the new proposed plaster standard does not tell the whole story and misrepresents several facts.
For example, the article (incorrectly) states that “onBalance’s concerns (regarding improper plaster workmanship issues) are based on research not pertaining to immersed (pool) plaster.” That is false.
For 15 years, onBalance has provided the industry with many studies conducted by forensic cement scientists – specifically on actual failed pool plaster that identified improper workmanship practices (including calcium chloride additions) as being the cause of certain defects and discolorations, such as white soft spotting (spot etching) and gray mottling/blotchy discolorations. (And they also determined that pool water chemistry was not involved.) The above findings are also similar to PCA and ACI findings for certain cement/concrete flatwork defects and discolorations.
The NPC’s own Cal Poly (NPIRC) study showed that adding calcium chloride in colored plaster resulted in discolored (blotchy) plaster, and that a high water/cement ratio resulted in early deterioration in balanced water. Yet, the NPC won’t address that in their standard and won’t adopt a good water to cement ratio standard that was used at Cal Poly that resulted in good looking plaster even though the water was occasionally aggressive. Why not?
The article also says that it is onBalance that the NPC disagrees with. No, it is the prominent cement scientists’ findings on pool plaster that the NPC has problems with and cannot refute. And since the NPC has no science or evidence to support their self-serving positions, they make excuses and suggest that everything has already been “hotly debated,” and cannot reach a consensus.
How does this industry reach consensus when the NPC won’t admit to those test pool results and realities, and all of the other documented plaster/cement studies? What do they really want?
So is it okay with the industry (including some in the trade press) that the plasterers don’t set good workmanship standards that would provide a quality and durable plaster finish that will not deteriorate and discolor once submerged in water? Is it okay that service techs and water chemistry are blamed for what are actually plaster defects and discolorations?
The NPC's proposed standard should include and be adopting good guidelines that are based on known science, and not allow poor practices that make it easier and faster to plaster pools, which can have negative effects on plaster.
It is time the pool industry is told the truth, and then we need to make this standard right for our customers. They deserve good workmanship and a durable swimming pool plaster finish.
Here is the link to the article, and please be sure to read the comments following that article.