How to clean discolored bluestone
by
Bob Hoffer
+5
I tried powerwashing and acid. Nothing works
Common Errors Cleaning A Bluestone Patio - YouTube
https://www.youtube.com/watch?v=IJprnlivBO4
Blue stone ages naturally and gets more beautiful as it changes color over time...I would leave it alone.
Make a paste out of Comet and water, brush on and shine with a soft toothbrush. Rinse well.
You might have to paint it with a roller. Call the place that did your stone, ask them what you can do. Good Luck!
http://www.premierpavers.com.au/about-us/news-info/2016/august/how-to-clean-bluestone-pavers.aspx
Did you seal it after you etched it with the acid?
The acid will just remove more of the surface...I agree with the suggestion of getting a pro opinion before you put anything else on this surface...paint sounds like your best option...they make a special porch and patio paint in gray which may be your best option also..