Plaster Installation
Ten Guidelines for Quality Pool Plaster There are proper steps to follow for the making of durable pool plaster. There are also improper practices that can lead to early deterioration, discoloration or other failures. Above is a ten-point checklist that will help achieve a lasting and discoloration-free plaster.
A Plastering 'Watch List' Taking control of the plastering process is within reach of any quality-oriented designer or builder, declares Kim Skinner. To help you on your way, he offers this step-by-step guide to managing what should happen on site before, during and after plaster application takes place.
Not All Color Pigments are Good for Pools It appears the plaster products that contain “organic” pigments become bleached (loss of color) over time when subjected to chlorine (an oxidizer). But products with “inorganic” pigments generally do not become bleached. Additionally, experiments which subjected both organic and inorganic pigments to LSI aggressive water showed that neither type of pigment lost their color from etching.
The Art of Good Pool Plaster Color An attractive plaster color (other than white) is often preferred by pool owners. However, it is very difficult for plasterers to produce a uniform and consistent color. The reality is that there will always be some minor shading (mottling) and variation in the color and can never be uniform looking like paint or fiberglass.
Installation Tips
- Take a sample from every batch of the plaster while it is being applied. Use plastic cups and write on the cup the date, time, address, and batch number. If there is a problem later, you can send the sample to the lab without having to take a core out of the pool.[1]
- The CSI is not applicable to new plaster finishes under 30 days old. It is actually necessary, to achieve a smooth and dense surface, to have about a +0.5 CSI during the first 30 days. This is because the plaster (cement paste) surface contains about 20% calcium hydroxide, which is somewhat soluble in balanced and slightly positive CSI water and can be dissolved away. The plaster surface needs to be "carbonated" before the CSI should be lowered to the acceptable and balanced range. And that generally is achieved during the first month under balanced water.[2]
Plaster Maintenance
The CSI is Reliable for Plaster-based Pools Using the Calcium Saturation Index (also known as the LSI in the pool industry) as a guide for maintaining proper pool water balance and to protect pool plaster, including quartz and pebble finishes, has become a mainstay in our industry for good reason.
All Plaster Finishes Should Last 20 Years All pool plaster finishes should last 20 years or more. However, some last only 5 to 7 years, and some less than a year before the plaster surface deteriorates, discolors, and looks terrible. Why the difference? Very often, plaster quality. Studies on pool plaster and cement/concrete flatwork have shown that poor workmanship practices have the greatest effect on durability, deterioration and discolorations. Various studies also confirm that water chemistry plays only a minor role.
Pool Water Balance is Not (Always) the Problem The Bottom Line - Maintaining slightly aggressive water (LSI or CSI of -0.1 to -0.5) is acceptable. It does not cause rapid plaster deterioration and discolorations problems on quality applied pool plaster. The plaster problems mentioned in the thread are prevented by following good workmanship standards. Right now, there are none.
New plaster on renovated pool- when to refill?
Reducing High Calcium Levels in Pools
High CYA Levels Do Not Stain Plaster Contrary to some misinformation that has lately been floating around in the pool industry, high cyanuric acid (stabilizer) levels do not cause gray discoloration, or white spotting (“spot etching” as some incorrectly call it) in plaster swimming pools, no matter what. And there are several studies that have documented that.
Plaster Problems
Being Blamed for Plaster Discolorations? Don't Get Hoodwinked Some newly plastered pools (including quartz and pebble finishes) may develop either white soft spotting (also called "spot etching" by some plasterers), streaking, calcium nodules, gray mottling discoloration, spalling (flaking), or severe craze (check) cracking within a few months after being plastered, and whoever has been maintaining the water is often incorrectly blamed for those plaster problems and defects.
Diagnosing Pool Plaster Problems'
White Spotting of New Plaster Pools The problem of plaster spotting has been an ongoing puzzle and controversy in the swimming pool industry for over three decades. The generally round, smooth-yet-unsightly white soft spots in new plaster pools have long been a source of contention among pool plasterers, and pool chemical service firms or pool owners, each blaming the other for the phenomenon.
How White Pool Plaster Turns Blotchy This experiment below explains how white pool plaster can become blotchy gray, and also have white areas mixed into the gray areas.
How White Pool Plaster Can Turn Gray One would think that when mixing white cement with white limestone aggregate, the final pool plaster product would always be white. But that is not always the case. Unfortunately, white pool plaster sometimes turns gray (or grey) either immediately or a few months after the pool is filled with water. So what causes that to happen?
Calcium Nodules in pools What are calcium nodules? In swimming pools and spas, they are small mounds, bumps, deposits, or “slag” piles of calcium carbonate which are formed from material that has been released from the plaster. The small calcium nodules are rough to the touch, hard, and generally gritty. Nodules may form singularly (far apart or sporadically), or many and close together along a crack in the plaster surface.
