Blue Stone and Paver Walkway Restoration - Help!

You've tried power washing?

Hi - Thanks for your response. Yes this is after power washing and removing old crumbling polymeric sand. I think it may need some kind of acid wash but not sure what to do next.

This site says scrub bluestone with vinegar and water.

But I will suggest scrub with sodium carbonate/sodium percarbonate mixed at 1 to 1.5 cups per 3 gallons water. Some deck cleaners use those chemicals, but cheaper source is Oxyclean, or cheaper yet is generic oxyclean. Best is to spray it on with pump sprayer, let it sit for a 10-15 minutes, then get down on your hands and knees and scrub with a stiff brush and rinse thoroughly. Yes, the scrubbing is a lot of work. They say (at least on decks) don't let it dry on the surface being cleaned - re-apply as required to avoid drying.

I purchased a 30% vinegar solution as a first step and will try a deep scrub with it. I will post some additional pictures with results. If that does not work I will try the Oxyclean recommendation. Thanks Again.