And no mention that calcium chloride (hardening accelerator additive) should not be used with colored pigments as manufacturers WARN against, as it also contributes to severe blotchiness. Plus, no acknowledgement that excessive water troweling can cause white streaking, soft spotting, or blotchiness to slowly develop over time. Amazingly, their bulletin does not mention anything regarding colorfastness and that (organic) color pigments can be bleached by chlorine or other oxidizers. The NPC has a Technical Bulletin addressing common color pigment problems. Of course, that allows some companies to underbid the quality-oriented companies. Question: Why would material manufacturers and plasterers sell and use non-colorfast pigments that will not keep their color? One reason may be that organic (non-colorfast) pigments are usually much cheaper than the superior (colorfast) inorganic pigments. Obviously, only pigments that are colorfast are appropriate for swimming pool finishes. However, it was also observed that when two (or more) color pigments are added to a plaster product mix to obtain a unique and special color, and the blue organic pigment became bleached and faded, the other color pigment(s), if inorganic and colorfast (often a gray or brown pigment), remains unaffected, intact, and becomes the dominate color. When an organic pigment, phthalo blue for example, is bleached and loses its color over time in chlorinated water, the plaster surface becomes “whitish” because it is made with white Portland cement. Additionally, experiments which subjected both organic and inorganic pigments to LSI aggressive water showed that neither type of pigment lost their color from etching. But products with “inorganic” pigments generally do not become bleached. It appears the plaster products that contain “organic” pigments become bleached (loss of color) over time when subjected to chlorine (an oxidizer). The onBalance team has conducted many experiments with various pool plaster products, such as pebble and quartz exposed aggregate products that contain color pigments. One would think that all color pigments used in pools are colorfast, meaning that the color doesn’t fade or become bleached in chlorinated water or in sunlight. The second issue is using quality color pigments (added to plaster mixes) that will hold up well for years and not lose its’ color in a swimming pool environment, which is the topic of this update. (Note: Some pool owners prefer the slight mottling variation that is normal for colored plaster). The first issue is to utilize superior workmanship practices to achieve good color, with minimal mottling, and no blotchiness, white streaking or soft spotting, which our previous email update addressed. There are two important issues involved when trying to achieve quality colored pool plaster that will remain durable, attractive, and the proper shade for many years.
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