Gray mottling problem

[yardoasis]

Just found this through a search, and I'm starting to think that I have this gray mottling problem by improper plastering.

What is THE solution to this? Short of re-plastering, of course.

 

[onBalance]

It would help diagnose the discoloration if you could post a picture of your pool.

Check out this thread: http://www.troublefreepool.com/threads/42827-Gray-Mottling-Plaster-Discoloration

If the pool has gray mottling discoloration, there are not good options or solutions to remedy the problem.
One option is an acid wash or acid bath. But those treatments do not always work and will shorten the life of the pool a few years because it etches the surface.

 

[yardoasis]

Hey, thanks for responding. Perhaps I should have tried harder to keep my questions related to this in only one thread, as I already have another on this topic... with 3 photos.

http://www.troublefreepool.com/threads/75741-Passed-SLAM-tests-still-seeing-plaster-stains

Note on the last photo, I spot-sanded the plaster in the shallowest part of the pool, and the stains disappeared or lightened noticeably. Maybe that gives a better clue to what I'm dealing with?

 

[onBalance]

I looked at the photos in your other thread.
Due to the fact that your pool is only two months old, IMO, it is not a calcium scale problem, at least, not the main problem. You stated that some areas are smooth, and some other areas are rough. So that puts a question as to the possibility of some scaling that you might be dealing with.

If the blotchy gray areas were calcium scale, simple sanding would easily and immediately remove the discolored scale. And ascorbic acid treatments might also remove recently formed scale on brand new plaster.

IMO, the second photo appears to be gray mottling discoloration of new pool plaster. Gray mottling discoloration is within the plaster surface, and should be smooth (if the plasterers troweled the surface smooth in those areas). It is not a "deposit" type of staining issue that can be easily removed. Consequently, initial or light sanding won't remove the discoloration, but further hard sanding eventually will. So will a strong acid wash. But of course, that will also etch the plaster surface, meaning, that plaster material is removed in the process of performing an acid wash.

Gray mottling discoloration is usually caused by the combination of overly late hard troweling (in various areas of the pool) and adding too much calcium chloride to the plaster mix.

 

[yardoasis]

Thanks for your response. That's what I was afraid of. Would it do me any good to contact the pool builder to complain? Maybe ask for a partial refund on the plaster job? I checked the warranty on the plaster, and it's not covered. If I go to the PB, they might just blame me for not properly balancing the chemicals and not acknowledge that their plaster guys did a boff up job of it...

What would you pool veterans do if it were your pool (that you bought and paid for)?

 

[HouTex]

I can't tell for certain how bad your plaster looks from the photos. My pool has had gray mottling pretty much within a couple of months of construction. It really isn't that bad and only really noticeable in low light conditions.

All of the documentation I was given and reviewed online about my plaster before it was installed said very clearly to expect some mottling. So I just live with it.

And you are correct about what the plaster company/pool builder will say. When my plaster guy came out to look at it he said it was due to "aggressive" water chemistry (and it wasn't--my CSI has always been well within the recommended range) and he offered to do a no-drain acid wash for $500. I passed on that not wanting to shorten the life of my plaster.

 

[onBalance]

It is up to you whether to pursue this or not.

Minor mottling (kind of a white cloudy effect on white plaster) is consider normal. However, significantly evident gray discoloration of white plaster (that can documented with pictures) may be a warranty issue. It may also get worse over time. I highly doubt it will disappear in time if someone tries to tell you that. And don't accept that your water chemistry is to blame.

I would at least approach the PB and make him aware of the problem. I would think that both the PB and plasterer want a good reputation of doing quality work, getting referral business, and avoid bad reviews and publicity. I don't think you paid for white plaster to turn gray.

If you decide to pursue, a good step is to have an analysis performed of the pool plaster for calcium chloride content, and determine whether more than the maximum of 2% (to the weight of cement only) was added.

 

[yardoasis]

Since some people think I have calcium scale, and others think it's gray mottling... here are some more pics, hopefully this will help us figure out what it really is. Before I do anything rash, that is.

Here's the "worst" area near the deep end:

Spa area... look at the walls:

Shallow end near the steps:

Steps:

The discolorations really show when it is shadowed from direct sunlight. On direct sunlight, I don't see anything and the water is sparkling clear. If you want more pics, I can take more and post.

Thanks everyone for your help!

 

[onBalance]

I will make my case for why I think the problem is graying and not calcium scale.
The second photo (of the spa wall) has water drip lines going down. I believe those lines were caused by the finisher rinsing water on the tile to clean it at the end of plastering.
When water flows down a wall, it causes a loss of cement or weakens the surface and creates porosity. That in turn, lightens (whitens) the plaster color as water breaks it down over time. If the problem is calcium scaling occurring after the pool is full of water, then the calcium scale would simply cover up those streaks and turn everything gray uniformly. The entire wall would be gray.

Let's also remember that calcium scale is white until dirt and metals attach to the scale.
I would suggest that you feel the dark gray areas in general and determine whether the surface is smooth or rough. If rough, a little sanding would make it smooth and remove the gray.
If smooth, then I highly doubt that the problem is scale. But that is not to say that there isn't any calcium scaling somewhere that may not have been brush sufficiently when new. But you will know it by the roughness or that the surface is gritty.

 

[yardoasis]

Very interesting, and now I'm convinced that this is a gray mottling problem. I still think I do have *some* scaling with dirt and organics attached, which I can sand off.

I'm still debating on how to approach the PB about this... I know I should be nice about it because I might need their business in the future.

I've read about Zero Alkanity treatment (aka no drain acid wash) for gray mottling, and that it *should* work, but is not a guarantee. I might try this in the offseason.

Or I could spot-sand the spa walls (2nd pic) and see if the discoloration comes off... and if it does, I could tape waterproof sandpaper (100-120 grit) to my pole brush and sand the entire pool? I suppose that would also shorten the life of the plaster, just like an acid wash would.

In the grand scheme of things, a couple years off the plaster lifetime of 15-20 years shouldn't really matter, right?

 

[yardoasis]

Or I could spot-sand the spa walls (2nd pic) and see if the discoloration comes off... and if it does, I could tape waterproof sandpaper (100-120 grit) to my pole brush and sand the entire pool? I suppose that would also shorten the life of the plaster, just like an acid wash would.

Yep, the discoloration on the spa wall came right off on the spot I sanded. Calcium scale. Other spots didn't come off, however. Looks like I am dealing with more than one problem at once....

 

[yardoasis]

Ok so here's my action plan:

1. Gently sand the scale/mottling with waterproof 320 sandpaper. See how much comes off. If looks much better, we may just decide to live with what we got.

2. If the mottling is still unsightly, then contact the PB to complain. Reject any offer to acid wash. Possibly push for a re-plaster on their own dime.

 

[yardoasis]

Just tried sanding. While I was able to get the obvious dirt stains to come off, I could not make a dent anywhere else. Maybe if I sanded one spot hard enough, the mottle would lighten up noticeably (while clouding things up, too, and probably increasing the CH...). I gave up after 20 minutes, there is no way I can do the entire pool by dunking myself, sand for 15 seconds, come up for air, and repeat. LOL... what was I thinking??

Anyway, I'll let the PB know. And I'll be nice!

 

[onBalance]

You should use 100 grit wet or dry sandpaper. 320 grit is too fine.

 

[yardoasis]

You should use 100 grit wet or dry sandpaper. 320 grit is too fine.

Figured as much, but I couldn't find anything lower than 320 for wet/dry or waterproof sandpaper.

The plaster is getting worse

EDIT: I did find 100 grit wet sandpaper for sale online, but they're going at $75 minimum for 10 sheets! This is outrageous! I'll just look for cheap steel wool sponges that I can get from the grocery store under a few dollars, I expect using those will accomplish the same thing.

 

[yardoasis]

Wanted to update this thread.

The plaster is getting worse and worse, despite keeping a negative CSI and twice-weekly brushing. It's been 1.5 months of keeping negative CSI, so it can't be scaling, can it?

My PB contact is on vacation, and their subs are busy catching up due to all the recent heavy rains. Once he gets back, I'm going to hammer the PB to get someone to come over and take a look.

What are my options, and what should I push for?

1. Tell the PB to remove all of the plaster, and re-plaster it properly. At no charge. If PB refuses, demand a huge discount or money back.
2. Have PB do acid wash for free, and push for a discount proportional to # of years off plaster's life.

I understand the pros and cons of a full drain acid wash vs a no-drain acid wash in this situation, shortened life of plaster from either, etc, which is why I am hesitant to push for option 2... plus how can I be sure that the PB would do an acid wash properly? I like option 1, but how likely is it that the PB will play ball?

Do I have any other options??

 

[onBalance]

Give the PB a chance to acknowledge the discoloration, and what he will do about it. I think he should make the plasterer re-do it under warranty.

If no agreement is reached, I would drain the spa and get a chunk of plaster out of the drain area and have it analyzed for the "calcium chloride" content.
It will probably be higher than allowable amount of 2% of the weight of cement.
With that information, I believe you would be able to have a basis to claim a plastering "defect."

Read this post: http://www.troublefreepool.com/threads/79555-How-White-Pool-Plaster-Can-Turn-Gray
And this post: http://www.troublefreepool.com/threads/79558-How-White-Pool-Plaster-Turns-Blotchy

 

[yardoasis]

At the risk of getting ahead of myself, how would I take out a plaster sample (something my wife won't be on board with)? And who do I send it to for testing?

I also checked the warranty, and the plaster is not covered. I'll post back when I hear back from the PB and what they'll do about it.

And, am I the only one on here who has this problem?

 

[onBalance]

There is no need to take a plaster sample from an area that shows visibly for now. Your spa should have two main drain covers, and you can remove one of them and take a hammer and screwdriver (or chisel) and knock out some plaster (at least a cubic inch amount) from underneath the drain cover.

This would only be a preliminary test to get an idea of the calcium chloride content your plaster might contain elsewhere and where the discoloration is. If you do this, you can PM me and I will give you a place to send the sample.

The pool plasterer should have their own warranty. Furthermore, construction defects are something that can sometimes be pursued regardless of whether there is a warranty or not, or the wording.
This type of problem is happening all of the time throughout the country. I get contacted often regarding problems like this.

 

[yardoasis]

Pool guys are coming to inspect the plaster on Tuesday. Wish me luck! I expect they'll blame the chemistry, and I'm prepared for that. Anything else I should ask, or prepare for??