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Thread: still unable to get rid of some white spots on diamond brite

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    Aquatica's Avatar
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    still unable to get rid of some white spots on diamond brite

    we've tried mixing with rain water, r/o water and now distilled water and still get some white spots and streaks showing up on new diamond brite finish. every contractor on the island is the same. I've seen way worst. our jobs are the best on the island but we want to see no white. I believe the white is paste. is the method of troweling we are using not right? should we be "skip troweling"? that brings the paste to the surface so it an be removed. maybe the guys are doing this. I will ask. we mix in large buckets with a mechanical mixer. don't think we are mixing wrong.

    any info would be very helpful. Many thanks!

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    Re: still unable to get rid of some white spots on diamond b

    If water is being added onto the plaster surface while troweling (especially towards the end), the results can be white spotting.
    Also, if too much calcium chloride is being added can contribute to that effect.

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    Re: still unable to get rid of some white spots on diamond b

    No finish is blemish free. Different batches combined at slightly different ratios, slight differences in mix water volume, mixing times, mix to application times, temp of the day, etc... all contribute.

    For most Diamond Brite finishes, after application, fill it with water, run the filter 24/7. drop the pH to about 7.0 +/- 0.2, bush 2x a day for a 4 to 6 days, then 1X a day for the next 3 weeks. Check the pH and alk, adding muriatic as needed to keep the pH at 7.0. This is important. This exposed the quartz and colored specks. Always brush from the shallow to the deep end with the skimmers off but drains on.

    Watch the pressure in the filter tank and backwash as needed.

    Use bleach to bring the FC to 1ppm after 4 days. After a week, bring it to 3ppm. After 3 weeks, start adding CYA and then calcium. Don't use powdered chlorines until the finish is 3 weeks old.

    No vacuuming or pool sweeps until it's 25 days old. The suction could cause delamination or wheel track lines to form.

    Scott
    Owner of - PoolGuyNJ LLC
    Expert Pool and Spa Repairs, Renovations, and Augmentation. Helping people decide what is the right gear for meeting their needs. Expectations Set, Expectations Met, No Surprises.

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    Re: still unable to get rid of some white spots on diamond b

    The guys troweling the finish should be troweling as hard as they can on the final pass.

    The purpose is to compress the cement into the tightest matrix possible (compaction). Since everyone has individual strengths, it is a good idea to have the guys go over each other work. That way it gets at least 2 good passed at compaction. This is called "hard troweling."

    Some cement paste may develop on the surface of the finish. This is usually due to one of two possible factors:
    1. TOO MUCH water in the mix - the water carries the paste to the surface, as it is displaced during troweling. It dries on the surface & leaves a white haze behind.
    2. The hoddy (guy mixing the batch) is adding calcium chloride to the batch to accelerate it's set. If too much calcium is added or if it is not mixed completely, it will result in white streaking. This calcium is weaker than the surrounding cement, so after it dissolves it may expose aggregate of a different color of finish.

    Calcium can lead to rapid drying & shrinkage cracks, the development of calcium nodules, splotching of the finish and/or discoloration in colored finishes. Too much shrinkage can also lead to leaks around the pipe penetrations & fittings (if they were left to be sealed by the plaster crews without using plaster seals or water stop flanges).

    It is best to not add ANY calcium. I know the realities of the plaster crews - slam, bam, pay me ma'm! The faster that they can get the plaster to set up, the faster they can finish it, and the faster they can get onto the next project (since most are paid piece work/by the pool x the amount of material).

    On our projects, our specifications state that absolutely NO calcium may be added to the any of our cement products (concrete, mortar, stucco finishes, or plasters). We are willing to tent the pool when it's too hot, and add heaters in the tent when it's too cold outside. Sometimes a poly tarp can be "pup tented" over the pool with a rope if the pool is small enough. We have developed a collection of many sizes, so now we can cover any sized pool.

    Yes, we are willing to pay the plaster contractor more, because we know that the crews may be standing around waiting for the plaster to develop a "set" before they can perform the final "hard troweling."

    Allowing the plaster to set naturally develops the strongest finish and most consistent color.

    We have used a technique developed by Randy Dukes of Aquavations, Florida to even splotchy colors and smooth rough finishes (when the start up was messed up by the pool service company). It is a process of performing an "acid wash" with the water in the pool. We use that process on every dark plaster finish to develop a deep velvety finish.

    It's best to contact the NPC (National Plaster Counsel) or Aquavations about obtaining a copy of Randy's book: Plaster Problems. It has this process outlined in the appendix.

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    Re: still unable to get rid of some white spots on diamond b

    Yes, all finishes have a few blemishes, but that is different from plaster jobs that have white spotting and streaking over various areas of the pool.

    My DiamondBrite pool is virtually blemish free. The plastering company agreed (with me) to not add any calcium chloride and also no water finishing, and no late hard troweling. The pool was filled with water that had 240 ppm of alkalinity, 200 ppm of calcium, and the pH was 7.8, making the CSI about +0.4. I maintained it that way for three months. There was no plaster dust, no spotting, no streaking, and today, after 7 years of never draining the pool, it still looks great.

    I agree with points 1 and 2 cited by ExpertWitness and the subsequent information on those issues.

    But as far as hard troweling; there is a limit on how much one can “compact” the surface. As plaster hardens, it is forming cement “bonds” and is creating somewhat of a “honeycomb” effect. Therefore, it is difficult to compress and compact the plaster surface once hardening is taking place.

    Furthermore, OVERLY HARD and LATE troweling can do two things that could be detrimental. One, it can break the cement bonds, which would weaken the product; and it can overly densify the surface, which can darken the color of the plaster. And again, adding water while troweling also breaks cement bonds and creates weakness, similar to what ExpertWitness stated above about adding too much original water to the plaster mix.

    I also disagree with the suggestion of performing an acid treatment to improve the appearance of a poorly done plaster finish. How can adding one gallon of acid for every 2,000 gallons of water be good for a new plaster or quartz pool? And that book states that if that acid treatment doesn't work, just double the dosage of acid! How can removing 200 to 400 ppm of calcium (as is stated) from the plaster surface and etching the plaster surface be a good thing?

    If the desire is to camouflage the plastering defect, then yes, an acid treatment may even out the color. But the fact is that the plaster finish will be etched and rougher than need be. I have seen many pools look very aged and stained within a year or two that had an overly acid treatment to correct the poor looking plaster job. I have also seen that acid technique not work and just make things worse. Does it benefit the pool owner if the pool needs replastering in a couple of years?

    Don’t allow poor workmanship in the first place, don’t always assume that the plaster workmanship is always done properly, and don’t always assume it has something to do with an improper water chemistry start-up.
    As for Aquatica's situation, since we don't have pictures, we really don't know what the problem is that he is dealing with, or what may be causing it. Much more information is needed.

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    Re: still unable to get rid of some white spots on diamond b

    I don't pretend to profess WHY it works, but Randy Dukes method WORKS! Much like Jock Hamilton's acid start-up procedure, it works! (United Chemical Corp, Piru, CA - god rest his soul)

    I disagree with your assessment of "hard troweling." While you may develop trowel burn, hard troweling will densify the matrix. The "honeycombs" within the plaster as microscopic and the plaster will not lift from the wall.

    We are talking about the hard troweling on the secondary application of plaster, not the initial layer.

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    Re: still unable to get rid of some white spots on diamond b

    If the plaster surface has white spotting or streaking (from high porosity), and an acid treatment is performed (as Randy Dukes suggests), and etch the plaster surface, that will make the overall plaster surface more porous and lighten it in color, which will blend in with the white spots and streaking. That is how it works (most of the time). But that program is only a cover-up of the original problem. The pool owner is left with a very aged plaster job that is not going to look good for very many months. When months later, and the plaster finish doesn't look very good, often, whoever is maintaining the water chemistry is then blamed for the change in appearance. Not right.

    Yes, hard troweling can compact and make the surface denser, and is beneficial up to a point. I didn’t mean to suggest otherwise. But there is a limit. As you stated, trowel “burn” (darkening) is a possible outcome if overdone.
    Gray mottling discoloration on white plaster can also result, which is largely due to extra hard troweling and densifying the surface. Randy Dukes acid treatment program will also often help to "lighten" (whiten) a gray mottling plaster surface. And again, it does so by making the surface rougher and more porous (under magnification). But that is not what one should do to a plaster surface.

    A very moderate hard troweling at the right time is what is recommended. That will result in a more durable finish. But if the plaster surface has already hardened to a certain point before the final troweling to get it smooth, it is virtually too late to trowel and get the surface smooth and do anything about it without harming and discoloring the surface.

    I like the fact that you do not allow calcium chloride to be added, and that you “tent” the pool in weather extremes, and take the time to do it right. Obviously, you are avoiding a lot of potential problems and discolorations, and are achieving a quality pool finish.

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    Re: still unable to get rid of some white spots on diamond b

    In regards to new dark colored plaster jobs, filling these pools with slightly aggressive water does cause a lot of plaster dust to form, which in turn, desposits onto the surface as solid calcium carbonate, making it somewhat white. Yes, an acid start-up will remove the plaster dust scale and result in restoring the dark color, but it will not be as dark as the original color. And again, the unfortunate fact is that it etches the surface slightly. I have performed many experiments comparing Jock Hamilton's acid start-up with the Bicarb Start-up on dark plaster. My experiments have shown a darker, more even color, smoother, and denser finish and result with the Bicarb start-up. And there are service techs and plastering companies that have confirmed the same on their colored plaster pools, including color quartz.

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    Re: still unable to get rid of some white spots on diamond b

    Many thanks for all the replies. I've printed them all out and will have a good read. Thanks again! B)

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    Re: still unable to get rid of some white spots on diamond b

    I should add that the r/o and distilled water we used was actually 5 gallon drinking water. not sure if that makes any difference. could this water contain some chlorine which might be responsible for some white marks?

    Update: just did a test on the r/o drinking water and could not detect any chlorine in it. I used a Taylor test kit. also tested for CC and came up 0. However I tested the distilled water we used with an AquaCheck electronic tru tester and found 1ppm of chlorine. However I found this AquaCheck tester to be very unreliable as compared with a Taylor drop test so we definitely don't use it at all now. Tried it out for 1 week hoping this electronic tester could help us save some test time.

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    Re: still unable to get rid of some white spots on diamond b

    I highly doubt that a few ppm of chlorine can affect a plaster mix. Also, consider that plasterers often add 1% to 2% calcium chloride to the mix, and that is equilvalent to about 5,000 to 10,000 ppm of chloride.
    There is no need to use distilled water for mixing. Regular drinking or tap water works fine. That is not the source of your problem. You could make sure that organics (like algae) are not in the water.

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    Re: still unable to get rid of some white spots on diamond b

    our tap water is very hard. about 300 ppm of CH in it and sometimes rust.

    This is our latest resurface project. owner is very pleased and is giving us more work but I'm a perfectionist and see that we can improve. would like to get our jobs 100% blemish free.

    we used sgm cool blue diamond brite. we used distilled drinking water to mix with and tried to use the least amount of water necessary. we also used skip troweling. our fill water was the reg tap water which was high in CH. we acid washed the new plaster and gave it a good wash down before we filled it. I then did 24 hr acid start up. brushed the pool and balanced out the water. we don't have the time or staff to brush twice a day for 2 weeks. we have to get in do the job as best as possible and move out to the next job.

    this was a small 3,000 gal pool surrounded by trees so it hardly got sun...

    http://a6.sphotos.ak.fbcdn.net/hphotos- ... 8902_n.jpg

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    Re: still unable to get rid of some white spots on diamond b

    I feel that tap water that has a decent amount of CH and TA is good for filling new plaster pools. It protects and prevents calcium loss from the plaster surface during the filling process and during the first month. If your tap water TA is also high, then I doubt you get very much plaster dust forming. What do you mean by skip troweling? Removing wet (high water/cement ratio) cement paste is a good thing.

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    Re: still unable to get rid of some white spots on diamond b

    Quote Originally Posted by onBalance
    I feel that tap water that has a decent amount of CH and TA is good for filling new plaster pools. It protects and prevents calcium loss from the plaster surface during the filling process and during the first month. If your tap water TA is also high, then I doubt you get very much plaster dust forming. What do you mean by skip troweling? Removing wet (high water/cement ratio) cement paste is a good thing.
    yes we like the high CH in the tap water. it saves us money. only problem is what else might be in the tap water but a D.E. filter gets rid of that. I would assume a D.E. filter will get any metals out as well as it filters down to 1 micron? just like the metal trap?

    We actually do an acid start up to dissolve the paste.

    skip troweling is a technique they use that brings the paste to the surface so it can be removed.

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    Re: still unable to get rid of some white spots on diamond b

    Dissolved metals in the water are smaller than 1 micron and don't generally get filtered out. However, D.E. filters will probably filter out some of the iron if it has been "oxidized" by chlorine or the oxygen in the water.
    But back to your original problem; metals in the mixing water would not cause white spots or streaking to show up once the pool is full of water. Neither would high calcium or high TA do that.

    If "skip" troweling brings the cream paste to the surface and which is removed during that same troweling process, then that is good. But if the cream paste is being removed by an acid treatment, then I consider that to be detrimental to the surface. My experience with acid startups on dark colored pool plaster (and quartz), is that it makes the surface slightly lighter in color. I hope the plasterers are not splashing water onto the surface while troweling. That will also cause lighter or whiter color, including streaking and spotting.

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    Re: still unable to get rid of some white spots on diamond b

    Quote Originally Posted by onBalance
    Dissolved metals in the water are smaller than 1 micron and don't generally get filtered out. However, D.E. filters will probably filter out some of the iron if it has been "oxidized" by chlorine or the oxygen in the water.
    But back to your original problem; metals in the mixing water would not cause white spots or streaking to show up once the pool is full of water. Neither would high calcium or high TA do that.

    If "skip" troweling brings the cream paste to the surface and which is removed during that same troweling process, then that is good. But if the cream paste is being removed by an acid treatment, then I consider that to be detrimental to the surface. My experience with acid startups on dark colored pool plaster (and quartz), is that it makes the surface slightly lighter in color. I hope the plasterers are not splashing water onto the surface while troweling. That will also cause lighter or whiter color, including streaking and spotting.
    They are acid washing, brushing and then washing and sponging/cleaning with the high CH tap water. I've seen a lot of pools and depending on the area the discoloration of the new diamond brite varies. Places with the most brackish water has very bad discoloration. Over the years some of these discolorations look rust like.

    Maybe sulfur in some of the water from wells. I'm not sure but we are definitely using drinking water to mix now. I want to get something like the metal trap..I think its called something else..made by the same people. and use it attached to the hose when washing the diamond brite surface. the tap water could have algae, sulfur, rust, definitely has high CH, high TA and some people who use wells close to lakes and the sea even have some salt. I think mixing with this type of water is a very bad idea and it's worth charging a little more to use good clean drinking water to mix. The wash water needs to be filtered using that metal trap device.

    I think we can almost get rid of all discoloration. Yes I've heard acid wash and acid start will darken the dark colors. I guess we would need to do another start up method for that. Most people go with cool blue which is also the cheapest and looks nice.

    next time I will take some videos and upload them so we can see the complete process going on here. Thanks for the feedbacks!

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