Two and a half months into a study designed to show why colored plaster pools fade over time, a pool industry experiment is beginning to yield results.

Recently, the research and consulting group onBalance devised an experiment hoping to show why some colored pools gradually fade while others retain their vivid shades over the long haul.

Is the fading caused by exposure to light? Do the colors lighten because they are being bleached out by chlorine? Is the fading caused by a lack of water balance because the water chemistry is being neglected?

Or perhaps some colored pools fade because of the chemical makeup of the pigments themselves.

Those are the questions onBalance is asking, and their experime nt, started at the beginning of November, is beginning to provide some answers.

On November 7, onBalance plastered two demonstration pools at their research facility in Tucson, Arizona.

The team’s working hypothesis is that the primary reason some colored pools fade is because of the chemical composition of the pigments. Specifically, they believe that colored plaster made with organic pigments will not retain its original vivid brilliancy over time, while colored plaster made with inorganic pigments will hold up indefinitely.

To test this, they’ve plastered two pools in four sections: Some containing only inorganic pigments; some containing only organic pigments; and some containing a blend of both inorganic and organic pigments.

They plastered two pools in this identical manner so they can measure whether aggressive water versus balanced water has any additional effect on the color loss.

They’ve also plastered small samples (coupons) as controls. These coupons contain the same pigmented plaster mixes and are being kept in the dark so that the team can later compare any color loss in the pools to the controls.

Here are the results so far: Sections 1 (Inorganic) were plastered with straight inorganic oxide of cobalt and aluminate, commonly referred to as cobalt pigment. So far, there is no color loss in either the aggressive or balanced pools relative to the control.

Sections 2 (Mixed) were plastered with a combination the of inorganic cobalt with organic copper phthalocyanine. In both the aggressive and balanced pools, the plaster is beginning to lose some color compared to the control, but it is subtle.

Sections 3 (Mixed) were plastered with a blend of organic copper phthalocyanine and inorganic chromium oxide green — a combination often used in exposed aggregate pastes. In both aggressive and balanced water, these sections are showing a dulling of the blue and starting to show slight undertones of green-gray.

Sections 4 (Organic) were plastered using only organic phthalocyanine. In both aggressive and balanced water, these sections are just starting to show some whitening, going from a pretty blue to … a pretty blue with whitened patches.

In both aggressive and balanced pools where any lightening/fading of the plaster has been observed, the bottoms of the pools show a more pronounced color shift than the sides. onBalance’s Que Hales said it has been exciting to see the beginning of these effects.

“It is fun to see real-world results after demonstrating these effects in a lab setting,” Hales said. “We will keep you posted as we continue the process!” Study

From page 15

Methods

The difference between the two pools (Pool A and Pool B) is water chemistry. Pool A is being maintained with aggressive water. Pool B is being maintained with balanced water. The target chemical balance ranges are: In the absence of cyanuric acid, onBalance is manually dosing the pools with liquid chlorine (sodium hypochlorite) on a daily basis, maintaining 5 ppm. Cyanuric acid will be added to the pools starting in late March. The chlorine will need to be stabilized by then, and adding about 40 ppm of cyanuric acid will also have the effect of lowering the LSI by about 0.1 in each pool.

To keep the calcium in the target range (because of concentration that happens when evaporation takes only pure water and the replacement water has calcium in it) they have occasionally added soda ash to precipitate calcium, which they then remove with filtration. Also, vacuuming to waste and replacing the lost water is used as needed to dilute built-up dissolved solids.

Pool A

Pool B