Sat 7 Nov, 2009 10:39 am
We have a flagstone patio that is turning black in places. At one time we had a charcoal grill sitting on it and it appears to maybe be discolored from ashes; howeve, it has spread. There is one very large area and a small area unassociated with the large stained area. Could it be some kind of mold. Our humidity is normally 10% to 20%. Anyone know how to clean it?
If there's mortar in the joints, be careful. If it's concrete, no prob
personally I'd try a bleach/water solution first.
It could possibly be oil or grease from the BBQ. if thats the case try a degreaser (Automotive shop). aplly the degreaser as instructed. Wash the degreaser off and apply liquid dishwasing solution.
Allow dishwashing liquid to stand for several hours before washing off.
use a pressure washer to remove any ingrained particals.
if the stain still exists
try hydrogen peroxcide: apply this and leave in the sun for several days. rinse off with a hose
If the stain still exists
use chlorine bleach.
Wash the whole area with chlorine bleach so as to keep the colour even.
with chemical application UV (sunlight) may increase the action