Become a TFP Supporter Pool Math Forum Rules Pool School
Results 1 to 10 of 10

Thread: Ten Guidelines for Quality Pool Plaster

  1. Back To Top    #1

    Join Date
    Jul 2011
    Location
    Arizona & California
    Posts
    770

    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 or discoloration. Following is a ten-point checklist that will help achieve a lasting and discoloration free plaster.

    1. The best cement/aggregate ratio is about one part cement to 1.5-1.75 parts aggregate (marble sand). If the plaster is too rich (cement-heavy), it tends to shrink and crack. If it's too lean (more sand), it will be less durable and potentially unworkable. Note: Always select high-quality and appropriate-grade cement and aggregate.

    2. When mixing plaster, a thick mix is best. Shoot for a water/cement ratio of .48 or less. Both the American Concrete Institute (ACI) and the Portland Cement Association (PCA) maintain that lower water/cement ratios produce better-quality cement that can withstand occasional exposure to mild acids.

    Lower water/cement ratios boost density while reducing permeability, porosity, shrinkage (craze cracking) and water movement within the cement product. Higher water/cement ratios, by contrast, cause excess shrinkage and cracking, and fail to offer adequate protection or long-term durability against the effects of water and the environment.

    3. A plaster mix should be mixed thoroughly, but also not too long. It is recommended that if the plaster has been mixed for more than 90 minutes, the plaster mix should be discarded.

    4. Plaster should contain as little calcium chloride set-accelerant as possible and never more than 2 percent to the amount of white cement. (Colored plaster, of course, should not contain any calcium chloride as it will lighten the color and become blotchy.) According to the PCA and other testing facilities, too much calcium chloride increases gray mottling discoloration and cement shrinkage. Several alternatives to calcium chloride that do not exhibit these characteristics are now available. The plastering of typical size residential pools shouldn't be completed in less than 4.0 hours.

    5. Never add water to plaster surfaces while troweling. Both the ACI and PCA have found that this may increase porosity, shrinkage, and variable (white or light) discoloration. A little water to lubricate the trowel, however, likely will not harm the plaster surface.

    Still, you never want to work,¯ or force, additional water into the plaster surface when troweling. Doing so can weaken the surface and may accelerate deterioration and caused spotting or streaking discoloration. Dark colored plaster is even more susceptible to white spotting and streaking discoloration from too much water troweling.

    6. Well-timed hard troweling can help produce a nice, dense plaster finish. But if the plaster becomes too hard before you have a smooth surface, the result is often dark gray discoloration and spotting, especially when calcium chloride is also used.

    7. Plastering in extreme weather conditions can lead to quality and durability problems. Industry groups specifically warn against using cement-based products in temperatures considered too hot or cold. The plastering process should take at least 4 hours to complete for typical residential pools.

    One solution is "tenting"¯ the pool, which protects the plaster surface (and the plasterers!) from the elements. In extreme dry heat, tenting the pool, and perhaps even directing air from an evaporative cooler beneath the tent, will help the plaster retain its moisture, and properly cure and harden without cracking.

    8. Do not fill the pool with water too soon. Though conditions vary, water usually should not be added for at least six hours after the pool has been plastered and finished. This should be enough time for the plaster to harden properly before being submerged in water. It needs to be understood that the bottom or "bowl" area of the pool is the last and final section of the pool to be finished, and the walls are finished first. The bottom area of the pool needs to hardened before being submerged in water, whereas the plaster walls don't see water until many hours later, which is the way it should be. Even balanced tap water can dissolve certain plaster components if the surface has not adequately hardened. The end result is often greater porosity and early deterioration, which may take a few months to show up as a different shade of color on the bottom of the pool.

    9. Soft or aggressive fill water can also deteriorate new plaster surfaces; and the effect is uniform. Ensure tap or fill water is balanced with sufficient TA and CH before using to fill the pool. Other new plaster problems such as drips, splotches, spotting, trowel marks, and hand- and footprints are the result of localized finishing errors.

    Surfaces may be further damaged by aggressive (acidic) startup techniques, which can cause additional uniform surface loss. By contrast, baking soda startups can neutralize aggressive fill water while promoting a superior plaster surface.

    10. Once the pool is filled, balance the water (and keep it balanced). Balanced water helps help preserve the plaster. Aggressive water causes uniform etching, while over-saturated water scales plaster. The Saturation Index is a good guide to prevent scaling or etching, water should have a saturation index value in the range of -0.5 to +0.5.

    With reasonably consistent maintenance, standard plaster has a life span of approximately 20 years. It is an inherently strong surface, and should be able to withstand real world¯ chemistry and/or maintenance challenges.

    Though pozzolans, blended cements and other materials are generating good results, there is still no substitute for solid workmanship. The above guidelines will benefit pool plasterers in the pursuit of a quality, long-lasting pool finish.

    For further info on plaster discolorations and defects, see this post: Being Blamed for Plaster Discolorations? Don't Get Hoodwinked

  2. Back To Top    #2

    Join Date
    May 2009
    Location
    Dallas, TX
    Posts
    781

    Re: Ten Guidelines for Quality Pool Plaster

    That's fantastic information and I appreciate the time you put into your post. However, how is a consumer to use it? Seems like we are still at the mercy of the plastering outfit to do the job right. Kind of makes me nervous knowing how many ways they can screw it up...
    20K gal IG plaster pool, Manually chlorinated with 6% bleach, 1.5 HP Sta-Rite Dura-Glas II pump, Pentair FNS Plus 48 DE filter, Polaris 280

  3. Back To Top    #3

    Join Date
    Jul 2011
    Location
    Arizona & California
    Posts
    770

    Re: Ten Guidelines for Quality Pool Plaster

    I believe that pool owners can discuss these guidelines with their Builder or plastering sub-contractor and let them know that you understand some of these issues. When asking for bids, you can ask if they will follow the above guidelines. Some of them already do. The one that agrees should be the one you hire.

    You can watch them, make notes, film them, and even pay a little extra for them to slow down by not adding a high content of calcium chloride and adding water while troweling. It would well be worth the price. And one important thing I forgot to include in the above post, is to suggest to the pool owner to take two paper cups and scoop in two different plaster samples of a recently mixed and fresh plaster material (before it is applied to the pool and hardens) and keep for future analysis if something goes wrong.

  4. Back To Top    #4

    Join Date
    Aug 2011
    Location
    Texas
    Posts
    45

    Re: Ten Guidelines for Quality Pool Plaster

    I wish I could have found your guidelines last year before our pool was built. I have a few spots in our pool/spa that are questionably over troweled with water and feel very porous, rough in a few spots. We had a reputable builder so it may not be much of a problem to get it corrected. Plaster is only 9 months old as well.
    12k gal gunite, Sunstone Plaster, Pentair IntelliFlo® VS+SVRS Variable Speed Pump, Pentair Intellichlor IC-40, Pentair CCP520 cart filter

  5. Back To Top    #5

    Join Date
    May 2009
    Location
    Dallas, TX
    Posts
    781

    Re: Ten Guidelines for Quality Pool Plaster

    Quote Originally Posted by onBalance
    I believe that pool owners can discuss these guidelines with their Builder or plastering sub-contractor and let them know that you understand some of these issues. When asking for bids, you can ask if they will follow the above guidelines. Some of them already do. The one that agrees will be the one you hire.

    You can watch them, make notes, film them, and even pay a little extra for them to slow down by not adding a high content of calcium chloride and adding water while troweling. It would well be worth the price. And one important thing I forgot to include in the above post, is to suggest to the pool owner to take two paper cups and scoop in two different plaster samples of a recently mixed and fresh plaster material (before it is applied to the pool and hardens) and keep for future analysis if something goes wrong.
    Once again, thanks so much for your time and expertise. I will be going through this process in the coming years(crossing fingers and toes).

    I get discouraged sometimes when I read about a replaster job lasting only around 10 years. Whoever did the plaster job in my pool really knew what they were doing. The pool was built in the late 1970s and it still has the original plaster. Yes it is kind of rough, but no delamination or any areas of looseness. It's in great shape for being 30+ years old!!!

    Hopefully when the time comes for reno I will be able to find similar craftsmen.
    20K gal IG plaster pool, Manually chlorinated with 6% bleach, 1.5 HP Sta-Rite Dura-Glas II pump, Pentair FNS Plus 48 DE filter, Polaris 280

  6. Back To Top    #6

    In the Industry


    Join Date
    Feb 2012
    Location
    Phoenix, AZ
    Posts
    728

    Re: Ten Guidelines for Quality Pool Plaster

    Thanks for sharing! Great post!

  7. Back To Top    #7

    Join Date
    Jul 2011
    Location
    Arizona & California
    Posts
    770

    Re: Ten Guidelines for Quality Pool Plaster

    I really believe pool owners can influence pool plasterers by simply telling them to not add more than 1 lb. of calcium chloride to 100 lbs. of cement, and telling them to not use excessive amounts of water while troweling towards to end of finishing. (They could sign a letter of statement for you). If plasterers time the troweling correctly and have enough personnel, they only need to lubriate their trowel slightly with some water, and perform the final troweling.

    On very hot and dry (non-humid) days, plasterers should place a tent or sun screen over the pool to slow down the hardening process, so that they don't need extra water to re-work the plaster.

    Tell your plasterer to make the plaster mix thick like oatmeal, and not soupy. Then take some pictures during the plastering process, then the plasterer will hopefully be extra careful to do the job correctly.

    I know of many pool owners that have had no problems when they communicated the above standards with their pool contractor. And now they have a good plaster job that is going to last more than 20 years with a good maintenance program. Far more than what is advertised by the NPC.

    I worked for my father who owned a pool plastering company, and our plaster jobs were lasting twenty years. I have also been servicing pools for over 35 years, and I know that most plaster jobs do and will last 20 years. Performing good workmanship practices is the key. Just make sure your contractor is aware of and agrees with the above plastering standards.

  8. Back To Top    #8

    Join Date
    Oct 2012
    Location
    Orange, CA 92866
    Posts
    15

    Re: Ten Guidelines for Quality Pool Plaster

    Wish I read this prior having our pool replastered. Its a colored plaster (light gray) with quartz.
    The stains and discolored areas are probably results of techiques used by the plastering Co.
    They did use calcium chloride (which I read shouldn't be used in colored plaster)
    And they started filling the pool as soon as the last guy walked out of the pool.
    I cannot tell if they used water when troweling because I wasnt home, but the marks on the surface described here looke dlike they did.
    I have been trough **** last 5 plus months since they replastered the pool and spend close to $600 worth of chemicals that I probably
    wouldn't if they did everything right. Just recently I had to drain about 1/4 of the pool because of high TA and high Ca which was direct result of
    them trying to neutralize the pool with soda ash after in pool aggressive acid start up, they used 16Gal in 28K Gal pool (which only helped the stains partially).
    I think they did what they thought were hired for. Plastered the pool. Do I like the result ? No.
    6K for quartz I don't think was a bargain where I would settle for lower quality finish.
    S. California
    28K 36x22 gunite IG pool with attached spa, Quartz plaster, Pentair VS pump, DE Pacfab filter, Raypack heater.
    Pool replastered June 2012

  9. Back To Top    #9

    Join Date
    Jul 2011
    Location
    Arizona & California
    Posts
    770

    Re: Ten Guidelines for Quality Pool Plaster

    Yes, the above guidelines are still accurate and valid.

  10. Back To Top    #10

    Join Date
    Nov 2015
    Location
    Ok ok
    Posts
    811

    Re: Ten Guidelines for Quality Pool Plaster

    This thread will prove to be very valuable to me, I intend on a plaster job in the next few weeks. I will discuss all of the recommendations with the individual doing the job. He's been doing it for over 20 years so hopefully he will understand. I want to confirm one thing, he said as long as the temperatures remain ~40° or above, I will be good. Is this accurate? Where I live when this job is done the temperatures will likely be highs of 50s and 60s lows around 40 possibly a few degrees cooler. He says that is good weather?


    ~14K gallon - AquaRite AQR15 SWG - pool Newly plastered on April 9 2016
    TF100 kit - STA-RITE SYSTEM3 Modular Media Filtration - Model S8M150
    Pool water supply from on site water well = CH of ~350 and TA of ~350
    Doheny's Discovery Automatic Robotic Cleaner/Pentair Model 011018 VS Pump
    Sundance Altamar Hot tub separate from pool / central Oklahoma

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •