We want to return our previously red painted concrete walkway to its original concrete grey finish. About five years ago, it was painted with red acryloic urethane paint. It's worn off in places over the years and looks ugly. We have tried a 2600 psi pressure washer and undiluted muriatic acid. The paint is still about 80% in or on the concrete. What should we use?

Undiluted muriatic acid wasn't actually a good choice for cleaning your driveway, although it is recommended to do so. It is highly corrosive and toxic and when used should be mixed with water (20 parts). What washed into the sewer undiluted came out in waterways and probably did more damage then you realize.

Have you tried a sand blaster ?

Tick

Have not tried a sand blaster

I advise against a sand blaster, It will remove more material than you want it to and will leave your surface uneven unless you have a very very steady hand.

I advise aginst a sand blaster, It will remove more material than you want it to and will leave your surface uneven unless you have a very very steady hand.

I don't think anyone would have this done unless it is professional. There are regulations involved in having sand blasting done.

Steady hand, yes, would have to be, but not a homeowner and I don't think there sandblasting equipment out there for rent.

Tick

Lots of paint stripper and scrapers. Do small sections at a time and put mess in old cardboard boxes. There are citrus based strippers but I don't know if they will work on urethane. You could rent an industrial sander.

A heat gun may work also.