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Thread: acid etching concrete

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    moodymike's Avatar
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    acid etching concrete

    Would one of the concrete gurus mind giving some good instructions on acid etching your cement pond?

    I had quite a few questions on the subject as I have never done it.
    How much water vs muratic acid?
    How long does muratic acid stay potent? I have some old stuff sitting from my pool, but I think its a few years old.
    What is the best way to apply it, just pour it in and spread it with a pushbroom?
    How long do you let is sit on the concrete?
    Is there and danger to it getting on pvc returns or abs bottom drains or skimmer?
    Any problems with areas that were patched with bond-kote?
    Once finished and you wash it down, will it do any damage to your pump or lines when you pump it out?
    thanks all in advance
    Mike

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    If you are using muratic acid from Lowes or HD or pretty much any hardware store, it is already diluted ( I think at 30%). Best advice is to start off low with a mixture of about 2% (of the mix from the hardware store) acid to water and see if the results are satisfactory. If not jump up to 4% and try from there. Usually you can jump up to a 10% mixture pretty safely. For tough areas 15% to 20% is not uncommon but you are better off doing multiple cleanings at 10% rather than a stronger mix. You start with low doses to see if the desired results are achieved. If not apply another higher dose. Thinking is, go low first as if you go higher and the results are too great, there is no going back. Rubber gloves and eye protection are a must.

    Muratic acid stays potent until it is neutralized. In other words it depends on the PH level of what you are applying it to. Normally in solutions around 5% or above you can get the faint smell of sulfur after applying it (if it is not windy). Once the smell is gone it is neutralized. About 10 minutes on most concrete.

    I like to use a large sponge to apply. Safer, keeps down the splashing and allows for a more consistent application. After that hit it with a stiff broom or brush. The more you work it in with a stiff broom or brush the better. Just remember to keep the agitation consistent throughout the work are else you end up with faint patches.

    In areas of question always test the area first. Never really seen it react with PVC, but I still would not get that much on PVC as I am sure it would bother the glued joints. Simple trick is to mix up about 10% ammonia to water and keep it handy nearby in a spray bottle. Ammonia is a base and will counteract the acid. Get on anything you did not want and immediately spray down the area with the ammonia mix and rinse with water.

    After about 10-15 minutes the acid is pretty much neutralized. Washing it down at that point should not have any ill effects on the plumbing. If in doubt let it sit longer to ensure it is neutralized.

    Muratic acid is not a wonder cleaner. Most likely it will take a couple of treatments and a lot of elbow grease to get the desired results.
    Last edited by ThisIsMe; 06-10-2011 at 06:23 AM.

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    There a directions for etching solution right on the bottle, follow those and you are Golden, wear a respirator as the gasses down in the pond will do a number on your lungs.
    Mike & Sharon Shaw
    Jonesborough TN

    http://www.koiphen.com/forums/attachment.php?attachmentid=437164

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    Why not forgo all that chemical hassel and simply powerwash the calcium off the concrete? It would be less expensive, take far less time, much easier to do, and no smelly fumes!

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    Certain coatings require acid etching the concrete to create a better surface for the coating to bond to.

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    Quote Originally Posted by moodymike View Post
    Certain coatings require acid etching the concrete to create a better surface for the coating to bond to.
    Mike

    I'm assuming (terrible thing, I know) that this is a NEW pond and NEW concrete, right. So, yes, you can use muriatic acid to etch it. We use a 12.5% (1qt to 8gals water)solution. We use a garden sprayer to apply it to already slightly dampened concrete. Once applied, as mentioned, agitate with a stiff bristle brush. Respirator and gloves ARE A MUST! Work in small areas, roughly 2'x4' to 4'x4'. Once strongly agitated, rinse with fresh water. We have never really found any problems of the mix coming in contact with the plumbing. If you're worried about it, just hit it with the hose immediately. The Ph of the hose water will neutralize it almost immediately.

    So, what coating product are you using that it gave you those instructions? Maybe we can help further.

    Mike
    Mike

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    I thought we were talking about etching concrete or is it cleaning concrete? Hopefully the OP will clarify. Huge difference between the two.
    Last edited by ThisIsMe; 06-11-2011 at 06:52 AM.

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