Muriatic acid is probably what you need. First use scrub brushes and a pH neutral stone cleaner/water mixture (I recommend TSP). Saturate the bluestone with water first, so that dirty liquid stays on the surface and doesn’t get sucked into the porous crevices deep in the stone. Also make sure you are wearing rubber gloves and other protective gear before applying the muriatic acid, which is highly corrosive. Keep your work area rinsed well with a hose. You may also consider renting a power washer (try Total on Nostrand near Home Depot). For areas that are repeatedly getting stained, consider applying a sealer. Good luck.
Jonathan
Modern Urban Design
mudlandscaping.com
I was cleaning green gunk off the stucco on my house with a sturdy scrub brush and a bleach solution (about half bleach and half water), and I tested it on some of the blue stone on my patio and it worked like a charm! Got rid of accumulated moss and dirt, and brought back the blue color of the stone.
I would, however, love to hear from anyone who might know if this is a bad idea. I just did it in a test area, and want to make sure I’m not somehow ruining the stone before I do it everywhere.
Muriatic acid is probably what you need. First use scrub brushes and a pH neutral stone cleaner/water mixture (I recommend TSP). Saturate the bluestone with water first, so that dirty liquid stays on the surface and doesn’t get sucked into the porous crevices deep in the stone. Also make sure you are wearing rubber gloves and other protective gear before applying the muriatic acid, which is highly corrosive. Keep your work area rinsed well with a hose. You may also consider renting a power washer (try Total on Nostrand near Home Depot). For areas that are repeatedly getting stained, consider applying a sealer. Good luck.
Jonathan
Modern Urban Design
mudlandscaping.com
I used detergent & elbow grease on mine except for moss/algae which I doused w/ bleach.
I was cleaning green gunk off the stucco on my house with a sturdy scrub brush and a bleach solution (about half bleach and half water), and I tested it on some of the blue stone on my patio and it worked like a charm! Got rid of accumulated moss and dirt, and brought back the blue color of the stone.
I would, however, love to hear from anyone who might know if this is a bad idea. I just did it in a test area, and want to make sure I’m not somehow ruining the stone before I do it everywhere.