I have a plaster problem

[Renee]

I have a pool plaster problem. There are greyish/brownish mottled areas--your posting that talked about "hydration" problems sound similar but I'm not sure . I've uploaded a picture and hope for some opinions on what my problem is. I have 20,000 gal chlorine pool with pebble tec that is 10 months old. I noticed something in some areas of the plaster soon after it was filled and was told it was just areas of more concentrated aggregate. Over time the problem has worsened but is only in a few areas all along one side of the pool----in the curve below the bottom step in the shallow end, on the sun shelf and the face below it, the wall/face below the spa water fall, and on the spa seat. The plaster company rep just came out and took a water sample that he said would be tested for iron to see if that was causing staining. He checked my ph and said it was in range---said chlorine was high and that high chlorine levels can cause staining. I know well enough that calcium and ph levels could cause plaster problems over long periods but I've never heard high chlorine levels are a problem. He said they would do a light acid wash to see if that gets rid of the stains and that we need to determine what is causing the stains to begin with--thus the water testing. He did say that if that didn't work, they would replaster. Looking forward to reading what you think. Thanks!

 

[JasonLion]

Re: I have a pool plaster problem

 

[onBalance]

Re: I have a pool plaster problem

Renee,
That is an interesting looking pebble tec plaster job. Perhaps you could post a picture of the plaster surface a little further away, like maybe 3 to 6 feet. Generally, high chlorine residuals would not cause a brown discoloration. I wonder what the plasterer deems as high chlorine levels? But the question needs to be asked. How, where, and what type of chlorine is added?

A light acid wash may resolve this problem if in fact it is iron staining. But if it is discoloration of the plaster and not metal staining, then an acid wash won't work and the plasterer may try to do a heavy acid wash which will just make everything worse. So you need to have a direct talk with him regarding this. Document everything, with pictures, and how much acid is used. A spot test should be performed first.

Incidently, high calcium and high pH doesn't cause "plaster problems," it causes scaling on the surface.

 

[Renee]

Thanks for the reply! They are planning to drain and do the acid wash soon. Regarding the spot test, do you mean try it on a small area of the discoloration to see if it removes it before washing the whole surface? I guess if it is going to remove it, they will know immediately? Do you have any guidelines for quantities on the acid? i.e. How do I know if they are going beyond light acid wash to a heavy acid wash? It is a 20K gal pool. Also, if it doesn't remove it, does that rule out staining and indicate a problem with the plaster itself?

I'm attaching 1 more picture. It is really hard to see the discoloration from a distance. It is a windy day too so I'll take a picture in the morning when calm and post it later.

Thanks again!
Renee

 

[Renee]

Forgot to add, that chlorine is added via inline chlorinator. Highest chlorine result has been 5ppm and only occurred a couple of times in winter. Definitely didn't have that happening in our warm summer time.

 

[onBalance]

You could do a spot test yourself, if you want to try. Get a plastic squeeze bottle and fill half with acid and half with tap water. Place bottle under water where the stain/discoloration is and squirt some acid on it. If the stain doesn't disappear, then it is a discoloration of the plaster.

A safer way would be to use 100 grit wet&dry sandpaper and sand a stain spot and see if it comes off. If not, then the same diagnosis. Seems to me that the plastering contractor should have tried one of those methods during his visit. If not, I wonder.......

The chlorine would not cause that discoloration or stain.

If the acid wash is performed, they should only use about one part acid to ten parts water as their solution. No stronger. If it doesn't remove the brown/gray immediately, then not a metal stain.

I am curious as to what area of the country you are located?

 

[Renee]

I wonder too!! Because that is something the first guy he sent out tried so obviously he knows that didn't work. He said if the acid wash didn't work they will replaster and I can only hope he means it. They are draining and doing the acid wash Thursday and told me replaster is scheduled for Monday if acid doesn't work. I'm sure he wants to avoid a replaster if possible. Are there any downsides to me for a replaster? I am in Texas.

 

[onBalance]

Depending on what caused the discoloration, the acid wash may temporarily work, but the discoloration may return a couple of months after the pool is filled with water again. Just the way it can be. The light acid solution should not be allowed to sit on plaster finish for more than one minute and then washed off by water.

When doing a replaster it is very important to achieve a good "bond" to the underlying plaster surface.

You may want to read the post titled "Gray Mottling Plaster Discoloration" listed on this Deep End forum.

 

[Renee]

Thanks for the information. I read your post on "Gray Mottling Plaster Discoloration"---that is what sent me to you. My problem sounds a lot like that description. Is there any "official" place I can get that information? Especially regarding the problem with the issue reappearing because if wasn't a stain but a problem in the plaster. Here is my worry--they say it is staining, they "remove" the "staining" with the acid wash as a courtesy. (that is what they told me they are doing as staining is not covered under warranty.) Then the "staining" returns and it's my problem. I suppose if it re-occurs in exactly the same spots, then that should be proof that it is the same problem and the acid wash just hid it for some time.

 

[onBalance]

I am sorry that you have a tough call to make. Maybe you should mention to them that acid washes always age the plaster finish somewhat and that you have a problem with that. And perhaps ask them how much calcium chloride was added to the plaster mix.

If it is a discoloration and not a stain, they will have to do a heavy acid wash to lighten the discoloration. Video some segments of the acid wash so that time lapses are documented and where the location of the discoloration is.

Lastly, consider whether the discoloration is major or minor, consider not letting them do an acid wash, and consider asking for a partial refund due to the problem. The current plaster finish is smooth and dense and will last 20 years with good care. Generally, after an acid wash, the plaster finish will not last as long. A few years will be lost. I guess it depends on how much you trust them to be fair with you.

 

[onBalance]

Okay, I have had a few minutes to think about this. My prior response is inadequate and poor. My bad.

If a few seconds of sanding or trying some acid on small discolored spots doesn't remove the discoloration, then I suggest not to have an acid wash performed. There is no point in going forward in that direction. It will only aged the entire plaster surface, hide the true cause of the discoloration, and make it tougher for you to get them to make it right.

It the brown stains are actually calcium scale with dirt embedded in it, then simple sanding or acid will quickly remove the brown stains.

There is no "official" website or agency to go to. But there are various documents, independent studies, literature, including from the American Concrete Association and Portland Cement Association that can be used to support what I have told you. I can help you pursue this issue if the contractor doesn't cooperate.

 

[Renee]

Thanks again for all the support and information! When you say, "brown stains are actually calcium scale with dirt embedded in it", is that referring to the problem caused from adding too much calcium chloride to the plaster mix or is that something else.

 

[onBalance]

Sorry, I meant to say "if" the brown stains was scale and dirt then they can be easily and quickly removed. If the stain is not quickly removed, then it is not scale and dirt. The addition of calcium chloride has nothing do with that. Calcium chloride has to with the graying of plaster.

 

[Renee]

Problem solved! The plasterer did not do the acid wash after spot test proved not to work. They are re-plastering. He said he believes abalone added to the plaster mix (a small upgrade we paid for to add a little sparkle to the plaster) is the culprit--says he's only seen it a few times but if it isn't cleaned properly can cause this type of worsening brownish staining. Only thing I see to dispute that is that it is only on walls, steps, seats and curves where wall meets the bottom--not on the bottom anywhere--why wouldn't it be there too. But in case, it is getting redone and hopefully is not a problem I will see again!! Thanks for the input and guidance.

 

[CB]

WOW,thats sounds like a pretty stand up company so far.Alot of people who have poor installation problems with their plaster have to really fight the plaster companies to get even a partial resolution,many don't even get that.Good Luck.

 

[TXaquaholics]

[deleted]

 

[Dschnell]

I'm curious too how the second came out and if you used the abalone again. I've heard of abalone doing this and as soon as I began reading your thread and saw the pictures I knew what it was. I just refinished my pool and did not get the abalone added purposely because I heard of this happening. I went with iridescent glass beads instead.

 

[Megsyperk]

Oh man, I think this might be what’s going on with my brand new re-plaster. I don’t know what product the plasterer used, I just chose the finish we wanted from the pool builder. I should have known to come here first and fully educate myself on this process. I need to post a thread for advice.