Ask the Expert Question-and-Answer Archive

by Ron Joseph

June, 2002

Repainting Concrete

Q. I am trying to find information on repainting a concrete slab that has already been painted. The organization I am involved in has their emblem painted on this slab and every year we paint our the design to give it a "fresh" look. This year we want to repaint a brand new design onto the slab, but we are not sure how to go about doing so. Should we sandblast the paint off the slab and start from scratch? Or is it possible to repainted the already painted slab with our new design??

A. You should be able to paint right over the old paint provided that you first thoroughly wash down the old painted surface and allow the surface to dry. I presume that you will be using an acrylic latex paint. If not, then please let me know.

Alternatively, if you simply want to remove the old emblem then you can sandblast the slab, or perhaps you can use a paint remover (chemical) to do this. If you use a chemical paint remover, you will need to thoroughly was it off from the slab after you have removed the emblem.

Once you have cleaned the concrete either by sand blasting or chemical paint remover, it might be a good idea to wash the concrete with muriatic acid as recommended by your local hardware store. Beware!!!!!! Muriatic acid is strong and must be used with care. Please refer to the instructions on the can or bottle, and take the necessary precautions to keep it off your skin and out of your eyes, etc. FOLLOW THE INSTRUCTIONS.

You will need to wash off the excess muriatic acid from the concrete and then allow the surface to dry thoroughly. Thereafter you should be able to apply your emblem.

I hope this works.