Austin Stone

R

Roger

Member
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.
 

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I would contact Diedrich Technologies and consult with them about the type of stone. They can tell you exactly how to clean it with what chemicals they have in the proper ratio. Web site is www.diedrichtechnologies.com. We use all their products. They've got a toll free you can use to ask them about it and they will give you good answers to your questions.

I would imagine they are going to recommend 101G Restoration acid to try first, but any of that is going to need to be applied by a low pressure applicator versus what you are talking about in downstreaming or X-jet. You get that stuff on the windows and you are buying them new windows. Same goes for plants and other materials on the house.

Watch that roof also, especially around the chimney. A lot of less experienced guys around here try and clean stone houses, break out the hydrofluoric acid and forget about the asphalt shingles or slate roofs. When they are done, you've got a great looking stone house with a roof that has white streaks going down the side and middle where the acid was washed off and permanently bleached the roofing material. A slate roof is a lot of money to replace.

I would recommend you not try and clean this entirely from the ground since you will want to be up close to the work near the top. Also, keep in mind that any chemicals you blast off the stone from the ground is going to throw it up and over the roof. You should probably look into applying chemical, then neutralizing it, then powerwashing with hot water. This way the Ph is acceptable to not destroy anything in the area around where you are working.

I would also recommend you look into face shields since this stuff burns like crazy when the wind changes direction. Make sure the shields and your gloves are chemical resistant also. Another trick we came up with is to smear a light layer of vaseline over your hands, arms, face, neck and ears. This will stop any acid that hits you from burning your skin.

Hope that helps.
 
the

reason that the chems in the last post will eat the glass and metal is because its HF ACID based[aluminum brightner] they add buffers to make it safer to use and not burn
 
The only problem with buffers is they tend to decrease the effectiveness of the acid itself. We've tried every imagineable buffered acid out there trying to find something to decrease the chances of burnt windshields and other problems on windy days. They just don't work as well. Try taking 50 years of steel mill carbon deposits off sandstone with a buffered acid and you'll understand better what I'm talking about.
 
Roger...
I am with Lance on this one...Call Diedrichs...Larry is the man to talk to there...He may go the alkaline way with 808, which is black encrustation remover followed by 707N which will neutralize the surface...But I have been very successful in similar type situations with 101.

Jordan
 
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