The National Plasterers Council has issued a public challenge to onBalance to settle the question of what causes spot etching.

The move comes after years of conflict between the two groups.

The NPC and onBalance, a research and consulting firm, have long differed on several issues pertaining to the cause of plaster problems, with the most contentious being questions surrounding spot etching, a phenomenon in which small, often white, spots form on a plaster surface.

NPC officials believe that spot etching is the beginning stage of etching deterioration, and is caused by unbalanced water chemistry. For their part, members of onBalance say "spot etching" is a misnomer and that the phenomenon doesn't involve etching at all. They also believe it results from flawed plastering practices, such as faulty troweling techniques, inclusion of certain admixtures and incorrect use of water.

Stating that it would like to settle the matter once and for all, NPC invited onBalance to participate in a study to see if spot etching will occur on pools plastered using the methods proposed by onBalance.

The written challenge was released to the trade press in mid-September and reads, in part, “[OnBalance claims] that ‘spot’ 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.”

To conduct the research, NPC proposed that six pools be tested at a venue or venues to be selected by onBalance. Three of the pools would be finished with white plaster, three in pigmented. OnBalance would coordinate and oversee the plastering and start-up of the pools (to address a disagreement between the groups over the best way to perform start-ups). NPC would provide parameters for the chemical maintenance, which would be performed by a member of the Independent Pool & Spa Service Association.

The water would be made aggressive to see how the material responds. “We’re not going to crank it up so hot,” said Alan Smith, an NPC board member who coordinated much of the group’s past testing. “We’re going to do real-life water scenarios. We’re going to be really fair.”

If onBalance’s thesis is correct, and properly plastered pools are immune to spots forming, NPC’s logic says, then it will be okay to run the pools with aggressive water.

The plastering organization chose to float the proposal through the industry media for transparency, Smith said. “Through the press, everybody would see that, and it couldn’t be spun by anybody when we put it out there,” Smith said. “It’s really important -- you see our intention and our heart behind this.”

Having just been notified of the challenge, onBalance is still assessing the proposal and preparing a response, said Que Hales, one of the three partners, along with Kim Skinner and Doug Latta. “It would have been nice if we’d known about this before it hit the press, but we didn’t,” he said.

Last year, a similar proposal was made by the APSP Builder’s Council, but talks broke down between the NPC and onBalance.

“We can’t continue to debate,” Smith said. “It doesn’t get anywhere. … Why don’t you just show us how to do it and let’s quit debating it. … If you’ve got a better way that will fix it, come show our industry.”

As far as onBalance is concerned, however, NPC isn’t addressing the real issue. “The experiment they’re proposing doesn’t even look at the spotting issue, it looks at etching,” Hales said. “[In onBalance testing] the labs repeatedly say that spotting is not an etching phenomenon. So why would we do test pools that are looking at etching when we already know that it’s not an etching problem?”