I had a church get in touch with me to see if I could give them some idea on just what is goign on with the sides of their building, it is block cement, and it has rust spots that have begun to show up all over the building (see pics)
My question to everyone
A. what are causing these
B. F9 do the trick to clean this and will it stay away
to my knowledge, there are a few reasons for those rust spots On that split face block. I have seen them a couple of times, but not too often. The first could be rebar in the block center that is rusting at a high rate from cavity wall moisture, and the block is so porous that it is finding its way out through it. The most common explanation that I have been told before, by a mason, is that iron ore is used to produce blocks and sometimes too much in a batch. In too large of a quantity, too close to the surface of the block, it can clump up and cause rust spots, because of oxidation.
I think F9 could remove it, but my guess is that it will be back.
Dan....here in Florida we have a lot of stucco homes which use the wire mesh anchored to the block home which the stucco adheres to. When the stucco cracks rain or moisture gets inside rusting out the mesh. This leaves the same run pattern as your pics...I have use F9 on these spots and has removed it. As John said it will come back over time if the cracks are not repaired by the customer.
Dan, judging from the areas where the stains originate, I'm guessing iron ore that was imbedded in the block. There will be no permanent cure for this. You might can get them off, but they will return.
__________________
Spray Wash Exterior Cleaning, LLC.
Cleaning North Florida, South Georgia, and Tallahassee!!!
Soft washing, pressure cleaning, and Safe roof cleaning!
Thanks for the input everyone. It looks like I will be cleaning these spots for this church on a as needed basis from now till? Hopefully once I get them all cleaned the first time I can stay on top of it so it wont cost them so much at once from here on out.
