Need Plaster Resurfacing Feedback - Pics

[-Matt-]

Call me crazy but I'm going the DIY route on this one and have done a ton of research on cementious and membrane solutions and think I am going to go forward with a cement based solution.

If the knowledgeable people here could look at these pics of the popoffs and the rest of the plaster to give me their opinion on what the issues were with the old plaster that may help me plan better on how much needs to come off and what I may need to consider in materials selection.

For the popoffs seem to be powdery between the hard outer layer and the inner plaster but I am not sure if that is just old plaster or a reaction product, it is white just like the plaster. The inner plaster (kind of concreteish some places but I found the brown area a half inch under the white in one of the pics so I assume that is the real concrete) the white I think plaster is not difficult to remove by pushing on it with a chisel but it is pretty solid. Some inner parts of plaster have been stained a tan color from the underlying concrete I think.

My guess is this pool is from the 80's or 90's and may have been maintained well but the water levels were so high in every department that I dont think the last owners ever changed the water, at all. Alkalinity was very high and I think the CaCO3 Alkalinity is 154 ppm out of the tap already and Total CaCO3 Hardness is 248 out of the tap. They have probably been topping off forever too.

I need help diagnosing this and determining if all of it has to go, just the delaminating sections, or maybe "just" the thin hard outer finish.

Thank you so much!

 

[kimkats]

Hi and welcome! What a job you are giving yourself! Were there is a will there is a way!

Here is something I want you to do.............take one of the chipped off pieces.....take it somewhere by water so you can rinse as needed. Put some muriatic acid on it. Be careful as the fumes from the acid alone are nasty! Does it bubble?? I will wait for your answer before I got any further.

Kim

 

[-Matt-]

Hi Kim,

Yes, it fizzes like an alka seltzer.

Matt

 

[kimkats]

Your pool is covered in calcium scaling. Here is one link where they talk about it: How to remove significant calcium scale and here is the link to it in Pool School: Pool School - Calcium Scaling

When you get your new plaster in you will can prevent this from happening by maintaining your water using the TFP levels. The key to this is having your own test kit as seen here: Pool School - Test Kits Compared

Here is a little light reading to get you started on learning our "language": TFPC for Beginners

I hope this helps!

Kim

 

[Dirk]

Having very little expertise on the subject, I can only offer a little devil's advocate type thinking. You're guessing your plaster is at least 28 years old, possible 38 years old. That's some sort of record. Kim has confirmed at least some of it (which means most likely all of it) has some serious calcium deposits to boot. Even without the calcium, I've gathered through some research that patching plaster is a losing proposition that doesn't work well, and is a temporary fix at best. When my six-year-old plaster failed, no one even brought up patching it. They jack-hammered it out, down to the gunite, and replaced it 100%. I just can't imagine trying anything less than that is going to be worth the effort involved. My gut about it: your plaster has reached its end-of-life (and then some) and needs to be replaced. Unless you have the means to remove it all, and replace it all, let a pro do it.

Otherwise, you risk a massive amount of labor on your part, trying to resurrect plaster that is done, only to find after you're finished that it is still coming apart on you. Do it right. Do it once. And then enjoy it for the next two or three decades, worry free.

 

[-Matt-]

Thanks Kim, appreciate the identification help and the friendly welcome.

To the other poster, I hear what your saying but most of it is quite solid and I will be going over it 100% and it will be reinforced with mesh or fiber. It will have polymers and silica fume basically making it completely waterproof and stronger. I also have done a lot of reading and people patch and go over it all the time, depends on the contractor and how much has come off. It isn't even 5% of the pool that has popped off. I want to spray the old stuff with silica fume treatments, I am not sure about the calcium buildup affecting that though. I am also considering membrane options as well. We'll see in the next few weeks. I have the time to do this right now, most people would not thats for sure. As for it being a record, well they may have redone it at some point, no idea. But I think the water here lended to adding not subtracting.

 

[-Matt-]

After reading the link on removing scaling Kim, I think I will spray a portion with muriatic acid and see how that goes. Thanks for the other links too, reading them. I think the current test kit isn't that great.

If I have to chip off just the top that may be realistic. It does not look like plaster to me underneath, well it does and it doesn't . It is white but has aggregate like concrete. Not sure what it is, they all are mixes of similar things.

 

[Dirk]

According to my stone and concrete surface guru, plaster is lower on the Mohs scale (of mineral hardness) than calcium, so the acid will be etching and removing the plaster more than the calcium.

When an acid wash destroyed my six-year-old plaster (there is that to consider on top of the rest of your plan), what I think I was looking at was the plaster's cream layer burned off in spots, large and small, which exposed the plaster's aggregate about 1/16" down (give or take). So I think plaster is similar to concrete in that regard. It has this micro aggregate giving it strength, that is worked down to bring up the cream layer. Acid washing will take out the calcium, and the attached plaster with it (that's pretty much what an acid wash does). So in your case, because you kinda want that first, old layer gone, maybe that'll work just right for you.

Testing a small patch sounds prudent. That's what the knuckleheads that destroyed my pool neglected to do (among other things).

Good luck to you. I would love to hear this works, and it sounds like you've done your homework about it.

 

[kimkats]

I think the under stuff is "pitted plaster" due to the poor water condition over the time before you got the pool. My thinking is it did not have enough calcium hardness (CH) when the plaster was first put on so the water leached it from the plaster causing the pitting THEN the CH got too high for too long and caused the scaling.

Matt-PLEASE use care when using the muriatic acid. The fumes are not to be taken lightly. Make sure to have a water hose right by you for rinsing any skin it gets on. Make sure to wear well fitted safety glasses as all times including when pouring it from container into spray bottle.

Let us know how it goes and take lots of pics!

Kim

 

[Dirk]

I think the under stuff is "pitted plaster" due to the poor water condition over the time before you got the pool. My thinking is it did not have enough calcium hardness (CH) when the plaster was first put on so the water leached it from the plaster causing the pitting THEN the CH got too high for too long and caused the scaling.

Matt-PLEASE use care when using the muriatic acid. The fumes are not to be taken lightly. Make sure to have a water hose right by you for rinsing any skin it gets on. Make sure to wear well fitted safety glasses as all times including when pouring it from container into spray bottle.

Let us know how it goes and take lots of pics!

Kim

+1 for safety measures!!

For the safety of himself and his pool, Matt needs to have a solution of acid-neutralizer standing by, not just water (which doesn't neutralize acid). Ammonia, or a baking soda mixture, something of that nature. If the acid gets away from him, it needs to be neutralized, not just rinsed away. (This according to my guru.)

As my pool guys were destroying my plaster, they were just rinsing it off the walls. Which is why my deep end took the brunt of it, 10x the damage down there, because the rinsed acid pooled down there and because it was never properly neutralized it kept happily eating away my deep end's plaster. The damage to the walls was mostly etching and some pock marks of various small sizes. Down at the bottom the acid stripped off plaster 1/4" or more deep, in large swaths, totaling to about 100 sq ft of exposed aggregate.

 

[kimkats]

Good call Dirk! I was on my way to call you to this thread! THANKS! When you say baking soda mixture do you mean baking soda &water in a cup, bowl, spray bottle?

 

[Dirk]

Not sure a spray bottle would work. To be honest, I'm not sure what is best. When I had a mixture of water and baking soda standing by for my first SWG cleaning, the baking soda separated faster than I needed. My guru uses ammonia, maybe for that reason. I don't know the best MO for neutralizing, I just know it's important to be ready when you're applying acid in an "unknown test sort of way." My guru measures the pH of the acid mixture before he applies it to anything and knows how to ready the neutralizer based on that pH. He's probably the preeminent expert in the SF Bay Area at what he does, so I don't question his methods, I just follow them. The baking soda mixture for the SWG cleaning session was my idea, not his. I didn't use it on the SWG, I just had it ready for spills around my pad, and ended up pouring it into the used bucket of diluted MA solution when I was done (because I didn't know what to do with a bucket of MA). Boy, what a reaction! Foaming and hissing. Just a reminder of how strong this stuff is, and how little I know about handling it properly! It's a cautionary tale. I really don't mean to sound discouraging to the OP. I envy is bravado for tackling this project. I've taken on some big stuff, but I'd be too chicken to attempt what he's doing. Kudos!! (But be careful.)

 

[-Matt-]

Thank you both for the tips and help. I do appreciate it! My sister just moved back to the area from San Francisco (she loved it but family is here). I had a quick visit and drove a load down here to Huntington Beach, CA. I also did not have thread notifications on by default so I fixed that! So mad because I just wrote out this message and I think because I had used the browser back button or maybe a quick reply it didnt save my message when I hit the back button on accident! ARGH! That's ok, first world problem.

So anyways, Kim I love your Avatar photo it is awesome! I think I will probably use my dog for my pic. So, I tried a little area (had dropped the chip in a cup of acid before). Wiping pure acid on the quartz (I think) finish did not do much, but pouring it on fizzed almost violently. So I think you may be right about it having been etched a bit first as it seems there are inner pockets that were later filled in. It looks almost crystally in places but it is not protruding at all. I poured but of acid on the white plaster underneath it in the spa and it fizzed a lot too though so that makes it a bit more confusing on what is what. Makes sense for the Moh scale but I dont know what is doing what now exactly.

Somehow one posted, through the little tree picture icon after I closed the window but second didn't work. Maybe my connection is slow here.

I went and bought some baking soda and will maybe get some soda ash too, so will use one of those when I do the whole thing. I am going to be out of town for about two weeks so no sense in etching it now. I was wondering to myself what would be best for bonding, but I think it is definitely necessary even if it removes some plaster. The question for me now is how much to remove. Dirk that sounds really frustrating about what the pool guys did with the acid! So is that when u decided u had to redo it? Sounds like I could use acids removal ability to ease taking off the top. We had a pool guy coming here for 3-4 months before I tested the water myself. I could not believe the numbers and think it is pretty shady to have CYA at like 350 or 550, can't remember, even if the chlorine was high! Felt like that was a crime of negligence for a professional to not say the water had to be changed. Prob didnt even test it for stabilizer. Anyways... I am not always impressed by "professionals". I will put a neutralizer in the water and maybe sprinkle it. Takes a lot of baking soda to neutralize battery acid. Don't ask me how I know. Naw, it wasn't bad was just trying to save an old battery.

The weird thing is, all the pop offs are on the bottom of the pool, none of it is on the sides except for the spa (which obviously got hot). There are a few deeper hollow sounding portions but not many so since they are on the bottom and I read that is not considered by defect unless it delaminates completely or cracks etc, I may just leave those. My plan is to use Alkali Resistant fibers in my plaster to reinforce it from doing the same thing and help prevent delamination. I will finish without the fibers. As it stands right now, I plan on etching and neutralizing, then spraying a concrete hardnder/densifier like a (acts as a water proofer and some as primer too!). Then probably a bond coat of cement and acrylic fortifier (helps bonding supposedly). Then a fiber reinforced cementious layer to prevent pop-offs and delamination. I will finish without fibers as I don't want a hairy pool three years down the line if they are not obvious immediately. Since the fiber layer is still setting it should bond well and I hope help with even the topcoat.

I was looking at just using Basecrete and Basecrete+ which are usually a contractor only product sold as a bondcoat but it is used as a plaster in France and comes in off white (good but we wanted putlre white). Honestly it is probably the best stuff out there but it is expensive and I would not be able to go buy more at the store. It looks like I will use Quickrete Heavy Duty Masonry coating and possibly the already fiber added Quickwall Surface Bonding Cement. The first one seems stronger and no fibers so I could added them for the first coat and not for the final and it would be a better matching bond wise. I am considering maybe adding quartz for the topcoat. I really wanted to use silica fume so I may add that to the mix, I think a little is unlikely to cause problems based on what it does. Would need to test. May also treat with a hardener after also. I would be ok with sharing the process of what i end up doing for sure. Hope I did not go into too much detail there!

 

[Dirk]

I've written and rewritten this post several times, trying to find a polite way to say what I think about your idea. And I finally concluded what I think about it really doesn't have much merit. I like your idea to experiment with your process before you commit it to your entire pool. Really hoping for you that it works out...

 

[kimkats]

You really need to take lots of pics and share them along the way. I am hoping for pics of the stuff you are using as well!

I can ask a couple of guys who do this kind of thing to pop in and give you input about what you are thinking of doing if you would like.

Kim

 

[MinerJason]

Your pool is covered in calcium scaling. Here is one link where they talk about it: How to remove significant calcium scale and here is the link to it in Pool School: Pool School - Calcium Scaling

When you get your new plaster in you will can prevent this from happening by maintaining your water using the TFP levels. The key to this is having your own test kit as seen here: Pool School - Test Kits Compared

Here is a little light reading to get you started on learning our "language": TFPC for Beginners

I hope this helps!

Kim

I'm very confused by this. Plaster is made up of marble dust and cement. Marble is calcium carbonate, so the plaster chips will fizz like alka seltzer when in the presence of a strong acid regardless of whether or not there's any calcium build up.

 

[Dirk]

Here is my simplified version of calcium in a pool, at least the way I've wrapped my head around it. Calcium stays in solution in your pool water when everything is in balance. If you don't have enough calcium in your pool water, the water will draw the calcium out of your plaster surface and etch and/or pit that surface while doing so. If you have too much calcium in the water, the calcium will fall out of solution and stick to wherever it lands: pebble, plaster, edge tile, waterfalls, etc.

The water's pH plays a significant role in how and when the above happens. You monitor pH and calcium and keep them in range, and you also use some math that incorporates the levels of those two elements together with some other factors (like water temp, salt level, etc), expressed as your CSI number, and strive to adjust all the various contributors to that math result to keep the CSI in a preferred range.

That is how one best combats the ill effects of having too much or too little calcium in pool water.

 

[-Matt-]

Dirk, no offense taken and I appreciate the honest feedback. Here's at least one pool owner who already did it though, Swimming Pool Plastering Do-It-Yourself Project
with essentially the same product (it was sold as pool plaster by quickrete then but if you look at the more detailed Safety Datasheet (SDS) for Quikwall Surface Bonding Cement (with the fiberglass) and the Heavy Duty Masonry Coating (without), they have all the same ingredients. They do show different specs but I believe that may be due to different ASTM testing being applied and having or not having the fibers (that or the composition ratios vary and some include the use of the Acrylic Fortifier, some don't). In any case Quikrete says both are good for ponds and pools.

His pool was in service for 15 years, it was 12 until he had "rough spots". He did use the fortifier and looking at the SDS's it is significantly better than the old cement and sand plasters of the past, he said the liquid added acrylics are better than the powder ones used in many "professional only" plasters. The Heavy Duty Coating is rated at 8000 psi, which is incredibly strong and it is a waterproofer, not just plaster.

This will not be an easy job, even though I will only chip out the spa and the couple hollow points. It would not be for most people time and effort wise but I can do both. It has required a lot of effort already research wise but future people will be able to know two examples that worked (assuming mine does) and they wont have to go through quite as much as me.

Here are the products:


----------

Quickrete Heavy Duty Masonry Coating

Heavy-Duty Masonry Coating | QUIKRETE: Cement and Concrete Products

More detailed SDS (safety data sheet, ingredients on bottom of page): Household Products Database - Health and Safety Information on Household Products

------------

Quikrete Quikwall Surface Bonding Cement

QUIKWALL® Surface Bonding Cement | QUIKRETE: Cement and Concrete Products

More detailed SDS: Household Products Database - Health and Safety Information on Household Products

------------

Quickrete Acrylic Fortifier

Concrete Acrylic Fortifier | QUIKRETE: Cement and Concrete Products

More detailed SDS: Household Products Database - Health and Safety Information on Household Products

**edit
The ingredients are on the bottom of the SDS links.

Here is the pool plaster he used, No 1800 (now discontinued and I believe renamed)

Household Products Database - Health and Safety Information on Household Products

 

[-Matt-]

You really need to take lots of pics and share them along the way. I am hoping for pics of the stuff you are using as well!

I can ask a couple of guys who do this kind of thing to pop in and give you input about what you are thinking of doing if you would like.

Kim

Thanks Kim, I would definitely like to be able to talk with people who know about these things. In relation to the calcium and all, I don't think that affects my product choice much at this point as I have narrowed it down to those Quikrete products for sure and the only considerations now are picking a densifier/hardener to treat the current plaster shell and concrete where I chip out, and then what sealer I use after or even during (integrally mixing in or spraying on during troweling for colloidal silica (product named Day 1 markets it for this purpose). I am also SOOO tempted to add Metakaolin or possibly silica fume to the cement mixes as admixtures. Both are pazzolans that convert excess calcium hydroxide and lime too at least for the former, into insoluble Calcium Silica Hydroxide (CSH) crystals in the pores and make it stronger, harder, less permeable, and more chemically resistant. The Quikrete products list Kaolin Clay already though which is what Metakaolin (MK) is made of. I wonder if it is really the clay or Metakaolin (Kaolin Clay heated up in a kiln or furnace). Not sure why i am capitilizing those still, lol.

I would really like to know what sealers have been used before and how it went. I dont think most have even ventured in that territory at all though.

I want to be able to talk to people who have plastered before and tried different bond coats, or skipped them even. I am a little uncomfortable about the bonding on the walls with the build up (WILL be etching and priming it with a sealer/densifier though), but the acrylic fortifier is made to help with that even on non porous surfaces. Would like feedback on that though.

At this stage, it is going to happen, already planning on it, but I could use helpful advice.

I will definitely share pics. If u want to look at the products now u can go to the linksI posted. I am going to add blue Spectraquartz to the pond finish. Possibly add more, bigger than the already included quartz sand to the pool if we like it in the pond.

 

[MinerJason]

I've been considering doing something very similar, and have done a lot of research as well. I also have experience with a lot of different masonry products and applications, but none with pool plastering.

A few thoughts. First, I see zero indication that there's any calcium build up on your plaster. But as you mentioned, that shouldn't really have any impact on your work either way.

I've done a lot of work related to bonding masonry products together, and IME the best bond coat is portland cement mixed with just enough liquid acrylic fortifier to create a slurry.

Applying a densifier to any areas you plan to plaster over is more likely to create problems with bonding than help you in any way. If you want to use a densifier, I'd suggest you apply it as the very last thing to the top of the finish coat.

Metakaolin is a great pozzolan additive which increases strength and also makes finishing easier. Just make sure to use at least 10% and no more than 15% portland replacement.

Keep in mind that preventing cold joints will be one of the largest struggles when doing it yourself. The guy in the link you posted above sort of got around this issue by dividing his pool into a bunch of small manageable sections with marble tiles. Unless you've got several helpers skilled with a trowel, you'll likely need to do something similar.

FWIW this issue is the primary reason I'm considering hiring a plaster crew. I've stuccoed several homes by myself, poured and finished a lot of concrete by myself, and sprayed and finished shotcrete in underground tunnels by myself, so I'm no stranger to tackling large masonry jobs. There's just no way I could plaster my pool myself without a ton of cold joints, and I'm not keen on the cost, time, or aesthetics of a bunch of tile dividers all over my pool.

Whatever you decide to do, I wish you luck, and look forward to hearing about your progress.