Some newly plastered pools (including quartz and pebble finishes) may develop either color fading, white soft spotting (also incorrectly called "spot etching" by some plasterers), white streaking (in colored plaster), calcium nodules, gray mottling discoloration (of white plaster), spalling (flaking), or severe craze (check) cracking within a few months after being plastered, and whoever has been maintaining the water is often incorrectly blamed for those plaster problems and defects.
Generally, it will be claimed that the pool water has been “aggressive” or "scaling" at some point in time, and even if the water has never been out of balance. But more importantly, aggressive water or scaling water does not cause the above plaster problems, and cement and plaster studies have actually determined that improper workmanship practices lead to those problems developing in pools and on concrete (cement sidewalk) surfaces.
So why are these unfair accusations happening? One main reason is because the National Plasterers Council (NPC) doesn’t do anything to stop it, and in some ways, enables it to happen.
Let’s examine this issue. The NPC and some plaster inspectors define “balanced” pool water within very narrow parameters and limits, but without any supporting science to back it up. The NPC states that water parameters (pH, TA, CH) must be maintained within industry “Ideal” ranges to be considered balanced, and disregard the “minimum and maximum” standards.
For example, NPC literature essentially suggests that pool water with an alkalinity of 70 ppm is considered to be out of balance and aggressive, even if the other water parameters make the CSI balanced, the NPC still considers that water “aggressive” and able to cause plaster problems.
Rain is about 1,000 times more aggressive than an CSI of -0.1, which the NPC says is unacceptable and aggressive. Yet, when it rains for a few days, cement sidewalks don't result in white soft spotting ("spot etching" which some plasterers call it), graying, or calcium nodules. Cement sidewalks and pool plaster are similar because both contain a significant amount of Portland cement which is what discolors.
So if the water chemistry is being blamed as causing one of the above plaster problems, and a NPC inspector or plasterer gives you a copy of the NPC Technical Manual, or a report by Arch Chemical or Cal Poly (NPIRC), or APSP and other literature, and suggests that it proves whatever it is they are claiming; don’t be hoodwinked or intimidated. Those reports don’t prove that out-of-balanced water causes those problems. In fact, they mostly indicate it is poor workmanship.
Today, some plasterers (sadly) advertise that plaster only lasts 5 to 10 years. But not long ago, plaster used to be promoted as lasting 20 years. In reality, it still can and does last 20 years when quality workmanship is performed. It’s not difficult to figure out who benefits and who is harmed when plaster finishes don’t last very long.
It is unfortunate that poor quality plasterers are being helped to avoid being held responsible for bad plastering work and results. That needs to change for the betterment of the swimming pool industry.
See these threads: White Spotting of New Plaster Pools
How White Pool Plaster Turns Blotchy
How White Pool Plaster Can Turn Gray
Calcium Nodules in pools
High CYA Levels Do Not Stain Plaster
www.troublefreepool.com
Generally, it will be claimed that the pool water has been “aggressive” or "scaling" at some point in time, and even if the water has never been out of balance. But more importantly, aggressive water or scaling water does not cause the above plaster problems, and cement and plaster studies have actually determined that improper workmanship practices lead to those problems developing in pools and on concrete (cement sidewalk) surfaces.
So why are these unfair accusations happening? One main reason is because the National Plasterers Council (NPC) doesn’t do anything to stop it, and in some ways, enables it to happen.
Let’s examine this issue. The NPC and some plaster inspectors define “balanced” pool water within very narrow parameters and limits, but without any supporting science to back it up. The NPC states that water parameters (pH, TA, CH) must be maintained within industry “Ideal” ranges to be considered balanced, and disregard the “minimum and maximum” standards.
For example, NPC literature essentially suggests that pool water with an alkalinity of 70 ppm is considered to be out of balance and aggressive, even if the other water parameters make the CSI balanced, the NPC still considers that water “aggressive” and able to cause plaster problems.
Rain is about 1,000 times more aggressive than an CSI of -0.1, which the NPC says is unacceptable and aggressive. Yet, when it rains for a few days, cement sidewalks don't result in white soft spotting ("spot etching" which some plasterers call it), graying, or calcium nodules. Cement sidewalks and pool plaster are similar because both contain a significant amount of Portland cement which is what discolors.
So if the water chemistry is being blamed as causing one of the above plaster problems, and a NPC inspector or plasterer gives you a copy of the NPC Technical Manual, or a report by Arch Chemical or Cal Poly (NPIRC), or APSP and other literature, and suggests that it proves whatever it is they are claiming; don’t be hoodwinked or intimidated. Those reports don’t prove that out-of-balanced water causes those problems. In fact, they mostly indicate it is poor workmanship.
Today, some plasterers (sadly) advertise that plaster only lasts 5 to 10 years. But not long ago, plaster used to be promoted as lasting 20 years. In reality, it still can and does last 20 years when quality workmanship is performed. It’s not difficult to figure out who benefits and who is harmed when plaster finishes don’t last very long.
It is unfortunate that poor quality plasterers are being helped to avoid being held responsible for bad plastering work and results. That needs to change for the betterment of the swimming pool industry.
See these threads: White Spotting of New Plaster Pools
How White Pool Plaster Turns Blotchy
How White Pool Plaster Can Turn Gray
Calcium Nodules in pools
High CYA Levels Do Not Stain Plaster
How to Ensure a Quality Pool Plastering Job
For pool owners, pool builders, remodeling companies, and pool plasterers that want the best chance to obtain a quality and discoloration-free pool plaster job (including white, color, and quartz aggregate pools), the link below is to an article in WaterShapes (a pool industry publication) that...
www.troublefreepool.com
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