Austin Stone

[Roger]

Hi All,

Does anyone have a homebrew mix or have recomendations for something that will clean really nasty Austin Stone? The majority of the house is just patchy spots of mildew stains, but there is one large area back in a corner that is constantly shaded by trees and other vegitation that is really nasty. Heavy mildew and algae growing on the stone. See attached pics. I haven't bid the job yet, wanted to get some input first on what to use to clean the stone. Not knowing what would work well to clean it, didnt want to bid it low and then have the chem cost eat up the profits. Will be applying chems either downstream or with an x-jet.

Thanks in advance, your suggestions are always appreciated.

 

[Roger]

Here is a close-up of some of the nasty stuff.

 

[ron]

if

you are real carefull with aluminum brightner[hydrofloric acid] then use a soap
[2 stepping] i have never seen anything stand up to that. But it may burn the surface
test first how about some RENEW and hot water? talk to GLENN from ACE