In the late 1980s and early 1990s there was a large "outbreak" of plaster surface problems, including discolorations, mottling, and other such blemishes. The University of Florida was engaged, under the sponsorship of Florida's Building Construction Industry Advisory Committee, to do a study.

One particular phenomenon, dubbed "spot etching" was characterized as a problem that is "frequently round in shape, dime sized and starts in the area of the steps and swimouts"and which over time can acquire color from metal staining.

As a result of curing samples in DISTILLED WATER and noting that they LOST WEIGHT it was determined that this problem is a result of water chemistry! We have already published a comment on the plagiarism and inaccurate science in that report, and shown that NO SCIENTIFIC CONCLUSIONS can be made based on this report.

The key finding of the Dow Whitney report is that spot etching (which they did not actually create) could be equated to general etching (which we all understand already).

The 1998 National Plasterers Council Technical Manual

In the late 1990s the Technical Manual Revision Committee of the National Plasterers Council produced an update. For the first time, the manual contained specific text relative to spot etching (the previous manual only had a picture and caption). This text included a description:

IV. Possible Deficiency Spot Etching (See photo inside back cover)
Definition Spot etching is a condition where an area of the plaster surface is composed primarily of exposed aggregate, when the immediately surrounding plaster is smooth and is primarily composed of cement or a mix of cement and aggregate. Usually the exposed aggregate area is lighter in color than the surrounding non–etched plaster, and the 1/16th to 1/8th inch of plaster immediately surrounding the etched area is almost white, looking like a “halo” around the etch. Often the etched area, over time, acquires color from metals (such as copper) which penetrate the etched area. The spots usually are round, or begin as individual round spots anywhere in size from a dime to a quarter, although in severe cases spots develop close enough to each other to merge and become a large etched area.

Possible causes The cause of spot etching is currently unknown. Research is being undertaken

Although at the time both the "aggressive water" proponents and the "finishing issues" proponents had begun to solidify their views, it was agreed in committee (which included both plasterers and servicemen) that no one had at that time documented and proved their view. This upset many plasterers, and led to the expulsion of the involved service techs from the committee.

The Strategy or Agenda of the 2002 Technical Manual Revision Committee

Since the plasterers involved could not prove their position, they moved to the arena of a misdirected agenda. As mentioned above, their first step was to clear the committee of those who disagreed with them. When the committee was subsequently reformed, none of the proponents of the "plastering technique as cause" were allowed access to the committee. Even though they were then invited to submit material to the new committee in writing, not a single one of their submissions were included in the new manual.

Then, the writer of the new version, Jon Dongell, wrote to the former Committee chair in an email that the new strategy would be to simply reclassify the problem so it couldn't exist anymore: to claim that "spot etching" was merely a form of general etching deterioration, and therefore need not be addressed in the new manual - other than to mention that it was a form of etching. Here are a few excerpts from that email:

"Other plaster, concrete and cement trades/organizations/associations have "etching" defined very well. How did they deal with it??? They explain the cause of "etching" and not "spot etching" and not "highlighting". This easily allowed for a cause/relation to be developed. We know what causes etching, in general. There is nearly 100 years of documented research papers and books which discuss etching. It has already been done for
us. We simply need to refer to these references and move on."

In other words - redefine the problem and it will go way. So that is what they did.

The 2002 National Plasterers Council Technical Manual

In this version of the manual, all reference (both text and pictures) to spot etching was removed except for a glossary reference that simply stated that "spot etching" was a slang term plasterers use, and that it simply refers to a form of general etching deterioration. The reader is then directed to the manual section on etching. Without pictures or text, this leaves those who are unfamiliar with spot etching unable to see the difference between a general etching problem and the spotting problem.

The Result

This, of course, created a major stir in the industry. Since it was common sense to most that a smooth surface is not etched, that a so-called "spot etched" surface was perfectly smooth and dense - other than the fact that the spotted areas themselves are porous and become discolored, and that the plastering apologists had made an end run around the rest of the interested parties, the new manual was widely disavowed. The State of California, for example, which had used the 1998 manual as the official document of the Contractor State License Board, continues to this day to use the old manual rather than the new.

In spite of the new manual's claim to be "scientific fact" and supported by a century of documented research, and despite repeated demands by the service industry in the trade press that the NPC provide this supposed vast body of documentation, the NPC has stonewalled the rest of the industry to this day.

In order to try to cover their mistakes and confuse the past, the new Cal Poly study was undertaken.

For those who remain unclear: SPOT ETCHING IS A CONDITION WHERE ISOLATED SPOTS OF THE PLASTER SURFACE ARE OVERLY POROUS AND WHERE A LOSS OF CALCIUM COMPONENTS HAS OCCURRED. THESE SPOTS ARE SURROUNDED BY PRISTINE, INTACT, DENSE PLASTER. IF THE LOCALIZED SPOTS WERE NOT THERE, THE PLASTER WOULD BE GREAT. THERE IS NO EVIDENCE OF AGGRESSIVE ATTACK IN THE UNAFFECTED PASTE, WHICH USUALLY COMPRISES THE VAST MAJORITY OF THE SURFACE. LAB ANAYSIS OF THE EXPOSED AGGREGATE IN THE AFFECTED AREA SHOWS NO EVIDENCE OF AGGRESSIVE ATTACK. PROFESSIONAL FAILURE ANALYSIS LABORATORIES, INCLUDING THE SUBSIDIARY LAB OF THE PORTLAND CEMENT ASSOCIATION CONCUR THAT THIS IS A WORKMANSHIP-CAUSED ISSUE... NOT A RESULT OF AGGRESSIVE WATER. To see these studies, please review the case histories on the onBalance main page. All of the case histories presented include professional failure analysis. Specifically the case history labeled oB-00015 contains both an RJ Lee Group analysis and a CTL analysis of the same pool. Here is also a copy of the CTL statement specifically referring to their independent peer review of the RJ Lee Group results. Suffice it to say: other experts disagree with the NPC and with Cal Poly: "Spot etching" does not equal "etching deterioration". (back to the list)

Does higher hardness = better surface durability and superior aesthetics? The Cal Poly researchers have appeared to equate surface hardness with surface durability and aesthetics. However, they did not address the rationale behind that assumption. Conventional thought is that durability and aesthetics are much more affected by density (porosity) than psi. Therefore, statements mentioning superior strength at a certain point in the plaster's lifespan is not necissarily a good indicator of whether that plaster will be able to hold up well in water. What we do know is that THE MOST IMPORTANT FACTOR IN SURFACE DURABILITY IS WATER:CEMENT RATIO, since excess water creates surface porosity and decreases density. We also know that calcium chloride increases porosity. (back to the list)

Did they successfully mimic pool water chemistry in the test? The difference between the Cal Poly researchers target chemistry ranges vs. what they actually maintained is significant. A look at their published graphs shows that OVER HALF THE TIME THE CHEMICAL DATA POINTS IN THE GRAPHS ARE OUTSIDE THE TARGET RANGES! Here, for example, is the pH graph from page 41 of the report:

The scale ranges from pH 0 to pH 13, and gives data points (chemical readings) for the pH over a span of 300 days (about 10 months). The five lines represent the readings from the five different basins which contained test coupons.

Here we have superimposed a band from pH 7.2 to pH 7.8 - the Cal Poly researcher's target range for pH. How many of the data points are inside the yellow band? The readings on the graphs for alkalinity and hardness are also more out of range than in. How can you make conclusions about water chemistry being "balanced" or "aggressive" when you don't maintain the chemistry in those conditions?

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Is the $500 price tag on a copy of the research report compatible with the spirit of previous industry exchanges? onBalance has distributed copies of our research, including lab research costing 10s of thousands of dollars to the industry AT NO CHARGE in hopes of coming to a resolution to the problem... (back to the list)

Is the research consistent with previous qualified research? The new research is not consistent with the RJ Lee and CTL material which has never been scientifically challenged. (back to the list)

What are the implications of their results to-date? The superficial interpretation made in the trade press, apparently based on summary material derived from the study, is that 4% of the balanced water samples "spot etched". Taking that statement at face value, David Dickman (editor of Service Industry News) rightly poses the following issue: "In the real world, it means that for every 1,000 pools plastered, there would be 40 customers out there with spot etching problems that were not caused by water chemistry. If I were involved in this project, I would be looking very, very closely at those 4-percenters to see if there was anything in the plastering process that caused them to develop problems where the other 96 percent did not." This is an excellent point - and we would add the additional question: What do you tell those 40 pool owners? That although they did everything exactly the way they should have ("the single most important parameter" - aggressive water chemistry - influencing spot etching deterioration does not apply to them), it was still their fault? (back to the list)

What can we really learn from the project so far? onBalance published recently in Service Industry News an article on the importance of waiting to fill a pool until the plaster has sufficiently set. In that article, we documented the fact that the longer you wait before turning the water on, the more durable the plaster surface. We will address this analysis the the Cal Poly technique in more depth later, but note: The sections they found most resistant to (general) etching deterioration were those which had the most time to firmly set and harden before submersion. In fact, the calcium chloride-accelerated sections were done first, in the morning, and the slower-setting non-chloride sections done at midday. It only stands to reason, then, that the accelerated sections were harder and more able to withstand submersion than the relatively fresh plaster which did not get the chloride acceleration! (back to the list)

Was the project adequately reviewed? Competent review of the research protocol (research plan or rules), could have helped the NPC and Cal Poly avoid many of the errors in the project. Is it the intention of the NPC to allow future phases of the research to be reviewed? The NPC has already handicapped their own study by removing opposing viewpoints from their research committee. They have released flawed conclusions to the trade press by rushing to judgement when they themselves should have been able to catch many of the mistakes, and others could have helped them catch the others. Hopefully, they will not repeat these errors in the next phase of the Cal-Poly project. If they had not rushed to judgement on this first phase they could have saved themselves and the industry from being subjected to yet more misinformation.

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