By Marcelle Dibrell
Unless you’ve been living under a rock, you are probably aware of the decade’s long debate between the National Plasterers Council and the consulting group, onBalance, concerning defective plasters surfaces.
The two groups, who represent the interests of plasterers and pool service professionals respectively, seem to disagree about everything.
With conflicts on topics ranging from new pool startup procedures, to proper plaster mixtures and troweling practices, both groups vehemently assure anyone willing to listen that they have gotten to the bottom of what causes particular plaster defects.
One of their main points of contention concerns the formation of white spots on a grayed background of what should have been a uniformly white plaster pool. The spots also occur on colored pools.
The spots occur shortly after a new plastering job is completed, and the problem appears to be irreversible.
Did the plasterer get the plaster mix wrong?
Was the plaster improperly applied?
Was the fill water bad?
Or did the spots arise out of improperly balanced water?
In other words, was it the fault of the plasterer or the pool service professional?
The stakes are high- law suits against the parties involved can get pretty pricey and both the NPC and onBalance are usually called in as consultants to give their expert opinions as to what went wrong.
Over the years, both groups have conducted numerous scientific experiments to identify the nature of the spots or to replicate the formation of the spots under controlled conditions.
Each group can tell you exactly how the defect occurred, and neither agrees with the other’s conclusion.
In the early 2000’s, the NPC helped to establish the National Pool Industry Research Center at California Polytechnic State University, San Luis Obispo.
One of the goals of their research
was to identify the cause of spotted plaster.
From their research, they concluded that aggressive water causes the spotting, and they dub the defects “spot etching”.
Meanwhile, a group of people on the pool service side of the industry began to question these conclusions.
Eventually forming the consulting group, onBalance, they also perform independent research on the causes of the spots.
From their research, they have concluded that the spots arise from a combination of adding calcium chloride, resulting in a gray background, and hard troweling work which disturbs the underlying aggregate, creating what they call “soft spots”.
Both the NPC and onBalance take issue with each other’s methods, scientific rigor and conclusions.
And why shouldn’t they?
These two very different causes for the problem lay the blame squarely on the shoulders of either the service professional or the plasterer.
Over the years Service Industry News has published updates on this decade’s long debate in an effort to see if the groups have come any closer to a resolution.
It seems that they have not.
That this tiresome debate continues to rage on is frustrating to a lot of industry professionals who would love to put it to bed. Alas, this cannot be while the debate continues.
In our last issue, we proposed a fresh start.
After all, wouldn’t we all be better off if we could seek and find answers to the unique problems of the pool and spa industry?
However, for this issue to ever come to a meaningful conclusion the scientific concerns and questions of both the NPC and onBalance must be addressed.
That might mean that the parties come together to plan and execute experimental procedures that finally resolve this matter.
Members of the National Plasterers Council welcome the idea of a fresh start, and have issued the following invitation:
For over two decades the National Plasterers Council (NPC) has been the utmost authority in the installation, startup, and maintenance of cementitious interior pool finishes.
Research, education, and certification programs have been at the heart of NPC’s mission.
NPC’s motive has always been to support the industry in delivering the highest quality value to pool owners.
Members of the industry have seen many changes in products and technology over the years.
Being responsible to deliver the very best the industry has to offer to the market has made the NPC hungry to learn about new products, techniques, and technologies to the delight of their customers.
The NPC has conducted research at Cal Poly State University on materials science, pool plastering materials, and application practices.
In the realm of materials the NPC has examined the use of white Portland cements, aggregates, water, pigments and calcium chloride. From this body of work the NPC has concluded that uniform etching is improbable to achieve.
This is based on the fact that curing and hydrating compounds within the matrix will naturally evolve into smaller concentrated areas of soluble materials that will etch first when exposed to aggressive water.
Therefore, the NPC recommends the use of harder, less soluble, pool surface materials. Also, that pool service specialists have a better understanding of how water chemistry affects different products in order to adjust the chemistry accordingly.
To this end, the NPC offers many materials on the matter, and features a certification program to further educate the industry in the proper startup, care, and maintenance of plastered pools.
In contrast to this conclusion, OnBalance has concluded that uniform etching should be the normal occurrence when pool plaster is exposed to aggressive water.
They claim that “spot” etching, or non-uniform etching, is a direct result of improper or poor troweling mechanics at the time of installation largely due to the misuse of calcium chloride.
They suggest the solution is the proper installation and troweling methods.
They contend weak and susceptible areas will be eliminated with proper craftsmanship.
As an industry, the NPC believes this issue should be resolved.
The NPC is interested to learn more about these “proper”, executable, and sustainable installation processes.
We believe it is time to put these theories to the test.
Let’s find out once and for all if OnBalance’s recommendation is realistic.
Here is NPC’s proposal to get to the bottom of this issue:
Set up six different test pools to establish consistency.
Three sets of two pools in areas that NPC will locate usable pools and would be convenient to the parties involved. We suggest the facilities at Cal Poly, or perhaps two each in the Phoenix area, Southern California, Northern California, or in some combination.
There should be three pools with white plaster and three pools with pigmented plaster. The NPC suggests medium-grey for the pigmented plaster.
Calcium chloride is optional
Cement strengtheners “pozzolans” will not be used.
All materials and measurements used should be recorded and documented including mixing times.
Delayed filling and tenting of the pool can be done if desired by OnBalance but needs to be documented.
The pool water needs to be aggressive in order to start the etching process. Since OnBalance believes that water chemistry, and startup methods, are not the cause of random or spot etching, we invite OnBalance to choose which method they would like to follow for all of the pools. The IPSSA Intermediate Training Manual by Robert Lowry lists on pages 88-97 four different start-up methods that can be used to start-up plaster surface pools. One of these methods is the NPC method and another one is the OnBalance “bicarb” method. The NPC will agree to OnBalance’s preference.
The NPC suggests IPSSA members participate and take care of the pools after plaster day and long term service.
NPC will locate the sites, make provisions for the pools, and provide all needed materials, and plater trucks. OnBalance will provide the finishers and mixer men. OnBalance will supervise, direct and sign off on the finishing methods at completion of installation.
NPC members will also be observers during the Plaster process. All mixing and troweling should be filmed and documented for future edification. The media will be invited to the event.
The testing could take months or even years to bear results.
If spotting or random etching occurs then onBalance’s theory fails.
Inspections, pictures and evaluations should be done monthly by NPC and industry designated members.
The only objective of this protocol is to determine if random or spotted etching (as opposed to uniform etching) of swimming pool surface materials is caused by improper troweling “finishing” techniques or is random etching an occurrence due to the nature of cement products when an etching environment exists?
All results will be published. Hopefully we will learn something that will help the industry or forever put the argument to rest and for all to work together for positive end.
As has been the heritage of the NPC, we seek to separate fact from fiction, and reality from theory.
To that end, the NPC hereby issues this invitation to OnBalance to do the same.
National Plasterers Council,
August 28, 2014. ■