Monday, October 24, 2011

Oh No! I got stain on concrete I didn't intend to stain! How do I deal with it?

Ask a Pro

   Q. -  Thank you so much for re-sending the download!  Also, despite our best efforts, some stain leaked on to the concrete under our taped plastic leaving a stain outside the intended area.  Any advice on how to lighten it? Thanks again!

Hello AnneMarie,
    A. -  A muriatic acid wash and a good stiff scrub brush should do it.
   Before I tell you how, I must tell you that it is extremely important that you ensure that you have plenty of ventilation and fresh air. Use mechanical means if necessary, such as fans in windows, one blowing in and one blowing out, etc. Ensure that you wear protective clothing. Particularly you should be wearing gloves, such as disposable nitrile gloves or another chemical and water resistant pair of gloves. Along with the other protective clothing such as long sleeved shirts, long pants, fully enclosed shoes or boots, goggles, dust or face masks, and/or respiratory protection as needed. Be sure to read all cautions, warnings, and instructions on the acid bottles label prior to handling, storing, and/or using.
   OK, on with the how. Mix the acid - 1 part acid to about 5 parts water. You can strengthen it if you need to, but try the 5:1 first.(5 parts water to 1 part acid)
   Here's the deal though, and this is highly important. The acid will yellow the concrete and eat away the surface if allowed to sit there for any amount of time at all. So it is extremely important to have a water hose running and ready, or to have a bucket of clean water with a mop sitting in it, on the ready.
   You dip the brush into the bucket of acid and water, then you shake off the excess into the bucket. Then you sit the brush down on the concrete and scrub it well yet quickly, being careful to not splash or splatter any acid/water mix onto yourself or your surroundings. Then you immediately remove the brush and place into the bucket or a predetermined safe place area, and then either quickly start rinsing the acid mix off the concrete with the water hose already running on full, or start mopping it up with the mop and the bucket of fresh water.
   It is very important to get all the acid mix rinsed all the way off of the concrete or all the way mopped up.
   You can repeat as needed until you get it scrubbed all the way down.
   As mentioned before, you can strengthen the mix by adding a higher acid to water mix if needed, but you should always start with the 5:1 or even weaker of a mix first, before going any stronger. Also as mentioned before, do not allow the acid mix to sit on the concrete. And be sure to not splatter or splash it.
   It is very important to be quick about it, but nothing is as important as your safety and the safety of others. And you do not want to create any additional problems to deal with either.
I hope this helps.
Earl Wayne Choate Jr., Ph.D.