Using cleaners on pavers over a pvc deck

[pavers4u]

Is it safe to use acid cleaners on pavers that are installed over a pvc deck?

[teacher]

Well, that answer depends on the type of acid cleaner you are using. There should be a Material Safety Data Sheet available for the cleaner you are using. Check the section on "reactivity data." This should tell you what materials are incompatible with the product you are working with. Hope this helps.

[pavers4u]

This is the first time I have been asked to clean and seal a deck surface, are there any other problems I could run into that are different from working at ground level?

[teacher]

Well, one that I can think of right off the bat is the issue of run-off. If you are using an acid cleaner (usually some concentration of hydrochloric or muriatic acid) you need to be aware of what the product is going to come in contact with when it runs off the pavement. Typically you would saturate all the surrounding area with water to nuetralize any overspray you may have. On a raised patio this becomes a trickier issue, especially if there is masonry below. Make sure everything gets a good soaking with water before you do it, and use an overspray board to keep your spraying contained.

[Paver]

Acid cleaners typically are not a problem with PVC (the same material your tank sprayer for the acid is made from), but the runoff, as you and teacher have discussed, can be an issue. Definately make sure everything is prewetted and kept wet until everything is done (including the drain spouts and side of the building). If the runoff is concentrated to one place (drain, spout, etc.) you can always have one person there constaintly spraying it with with a hose to further dilute the runoff.

[Derek]

Great answers and I know this is an old thread, but one pertinent question in my mind is why are you acid cleaning? Are you removing efflorescence, rust stains, dirt, mortar or grout stains, etching, brightening, et al ?

Many of these processes use different acids.

I wouldn't recommend the use of muriatic acid for any type of concrete or masonry product. Muriatic is another name for Hydrochloric Acid. The muriatic bought off the shelf can be virgin, but is often steel pickling or leather tanning byproduct. This can harbor contaminents that may stain the pavement you are working on. Muriatic acid is also not usually regulated for strength. Most muriatics range from 33%-40% in strong form to 7%-14% in their weaker shelf form. In a bottle that ranges from 7%-14% you do not know from one bottle to the next if what you will be using is up to TWICE as strong as the last. In the concentrate you are looking at 20% difference from low end strength to high end strength by volume. This can cause some serious damage as well as non-uniform results.

Depending on the type of acid, you may have to take more precaution (oxalic acid, which is typically a rust remover, can bleach most any surface it contacts included painted wood or vinyl siding, possibly even PVC; fairly strong hydrochloric can attack and discolor metal window frames and create dead spots on vegetation and landscaping that would normally not have any reaction to a regular efflo cleaner at moderate
strength; phosphoric tends to be a great efflo remover but doesn't do much damage to concrete or surrounding areas under normal usage)