Sidewalk chalk stained my new concrete patio

[r.e.d.a.l.e.r.t]

I had a new concrete patio poured just over a week ago and it looked perfect until my daughter and husband used regular sidewalk chalk on it. Now, even after several rain storms the chalk will absolutely not come off or out of the cement. It looks exactly like a grease stain but it's just normal sidewalk chalk that never stained any of our old concrete.

We have tried everything including letting the rain wash it, using a pressure washer, scrubbing with a baking soda paste, and even using Purple Power cleaner, but nothing has worked. I'm completely frustrated because the patio isn't even ten days old. I really want to paint it to hide the awful stains but I need to try every solution first. Does anyone who knows concrete have advice on what I should try next to remove these stubborn chalk marks?

 

[Alan]

It's a common problem with new concrete because it hasn't fully cured or been sealed. It leaves the surface highly porous and absorbent to the pigments and binding agents in the chalk. Try a poultice using a strong degreaser or solvent, like mineral spirits or acetone, mixed with an absorbent powder since pressure washing failed. Apply the poultice, cover it tightly with plastic wrap for 24 hours to prevent evaporation and allow the solvent to draw the stain out from below the surface before scraping the dried paste away and rinsing.