Gregg,

I'd use F9 2:1 (2 parts BARC to 1 part water) and spray on with pump or electric sprayer. I'd mist it onto a dry surface, allowing the product to dwell for a few minutes. It's ok if it dries, just hit it with low pressure, warm water (105-125 degrees) and rinse well. I think F9 will be your best bet.

-- Edited by Craig Harrison on Sunday 17th of March 2013 09:56:14 PM

You're welcome. The warm water is just helpful, not mandatory by any means.

Doug I think it's oxidation leaching from behind the signs as water drains from them. The 2% didn't put a dent in them. Didn't want to up the mix either as it was painted stucco and was worried I'd start stripping the paint. It was tough working at midnight as the parking lot lights wash out the stains and it was impossible to tell until the next day if I had success. Since I'm not only stop cleaning the stains I plan to do it when there's some sunlight.

I think it's some type of oxidation too or possibly rainwater is actually taking some of the color from the sign and transferring it on the siding.  Who knows.  This stain is usually really tough to remove.  I'm thinking to try F9 first and if that doesn't do it then saferestore.  BTW, we'll have a great, safe product for hard water stains soon that is phenomenal.

 

Here's the link to it on UAMCC: F9 Hard Water Stain Remover

 

The combination of our F9 BARC and F9 HWSR will give you the power to remove just about anything from any hard surface.  Another one of our trade secrets being revealed! :)

 

Also, for lighting we use those industrial lights like these from Home Depot or Lowes.  If your pressure washer has a generator you can just plug it in and away you go.  There are several types of this kind of lighting.

 

Gregg- you could also do a light brushing with a soft bristled truck brush after application of F9.  This would help. 

-- Edited by Craig Harrison on Monday 18th of March 2013 05:00:33 PM

-- Edited by Craig Harrison on Monday 18th of March 2013 05:05:07 PM

F9 is available at most major online retailers now.

I was gonna say that boat had sailed. Lol

Gregg Austensen wrote:

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Doug I think it's oxidation leaching from behind the signs as water drains from them. The 2% didn't put a dent in them. Didn't want to up the mix either as it was painted stucco and was worried I'd start stripping the paint. It was tough working at midnight as the parking lot lights wash out the stains and it was impossible to tell until the next day if I had success. Since I'm not only stop cleaning the stains I plan to do it when there's some sunlight.

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 yes, its an oxidation/metal reaction from the sign. Not biological growth at all! if f9 doesnt work, OneRestore will