Whats This?

[Doug Dahlke]

Anybody have an idea what this stain is and how to remove it? I don't think it is rust. It is under a canopy and similar stains are in a couple of other areas.

 

[Squirtgun]

It looks like rust that has migrated from some place else on the property.

 

[Doug Dahlke]

I know it looks like rust but this is under a canopy on an upper level. I guess it could have come from the hand rail there if they were unpainted and rusty at an earlier time. The same stain is in another area though where there is no rail.

 

[Doug Dahlke]

Here are pics of the canopy. It is not open so I doubt it leaked from there. I wonder if the railings were rusty once and when they were painted the prep work caused the stain.

 

[Mike Cooke]

it almost looks like someone spilt acid

 

[Paul Kassander]

I spoke with a concrete restoration specialist about it today and he suggested that it may be a mold or mildew growing in the concrete. The first thing he asked if it was a northern exposure. If the area gets little sun this could be the problem. He thought that perhaps moisture was leaching up causing the problem.

 

[ckingclean]

Do you have the job already?

Do some testing with your different chems on a small area with light dilutions and see what takes it off. Be careful because your chems will leak down to the 1st story!

 

[Doug Dahlke]

I did a test spot on this early this morning before the stores opened up. Used some Safe Restore on a small area and it took it right off.