When a new white quartz pool in San Diego developed numerous shrinkage cracks and very rough and sharp calcium nodules everywhere, the plasterer drained the pool and sanded it, charging the pool owner one thousand dollars for the work. The crystalline nodules began to form again soon afterwards, so the plasterer told the pool owner that a pool plastering expert and consultant would perform an inspection to determine the cause. The plaster inspector was also a long-time National Plasterers Council (NPC) Board member, but it is not known if the pool owner was given that information.
The inspector reported the following observations and recommendations.
1. The many random cracks were about 1.5 inches in length and had nodules on them.
2. The pH at the time of the inspection was 7.8, TA 80, CH 600, TDS 4400, (Salt content 2800), and CYA 50 ppm, so he calculated LSI as “0.0” and in balance. (Actually, the LSI would be about +0.3).
3. He claimed that a high TDS and low “carbonate” alkalinity (62 ppm) causes calcium to be “leached” from the plaster surface (even though the LSI was balanced).
4. He told the pool owner to purchase a Taylor K-2005 test kit so that he (pool owner) could accurately test the pool water.
5. He recommended draining the pool, sanding the plaster surface again, filling with fresh water, not adding salt, turning off the Salt System, and then properly maintaining the pool water. He wrote that, by reducing the salt content, TDS, and calcium, the pool surface should stay smooth.
6. The inspector stated that he “saw no improper workmanship or materials on part of the plasterer.”
After the plaster inspector report was provided, the plasterer stalled and/or refused to replaster the defective pool. About a year later, the plasterer went out of business. The pool owner was left with a very unsightly and rough quartz pool.
Later, a cement lab determined that the plaster mix contained 5 percent calcium chloride, which is excessive, and that the cracking occurred immediately after finishing and before the pool was filled with water. Excessive calcium chloride additions also contribute to calcium bleeding and the formation of nodules.
What enabled the pool inspector to render that erroneous conclusion? Disturbingly, the NPC Technical manual contains text that can be interpreted to support the inspector’s position, and enable plasterers to avoid responsibility for defective workmanship, including plaster cracking and nodules.
Are we as an industry going to allow the NPC to blame “plaster cracking and nodules” on water chemistry?