Karen Shane
5/7/2011
I had my metal (steel) roof installed a few years ago. I wanted to have it cleaned. I made the mistake of allowing the guy to use Bar Keepers Friend which contains Oxalic Acid. He scrubbed it on 3/4 of the roof in the hot sun (in the front of the house) and then went back to rinse it off. I now have a roof that looks streaked with black. I assume it ate through the coating and oxidized the steel. What can be done to fix the problem? My roof is unpainted. Thank you! (Photo taken late in the day so black streaks don't show up too well.)
Todd Miller
Classic Products, Inc.
5/7/2011
Is this an acrylic coated galvalume roof?
Karen Shane
5/9/2011
The description on the papers I have say "Corrosion resistant galvanized or galvalume preformed, coated, prefinished, metal panels." I assume I can get more information by calling the source where my roofer got the materials which is Met Roofing in Miami. Thank you!
Todd Miller
Classic Products, Inc.
5/9/2011
I am going on the assumption here that this is what we call a "mill finish" roof in one way or another. In other words, the overall appearance is silver / metallic. Let me know if that is not the case. Okay, I just re-read your original post and I see where you said it is unpainted so that is indeed what you have. I am sorry ... I do not have any good ideas on this. My hunch is that the current appearance cannot be reversed. It may lighten up a little over time but probably not dramatically. Your roof could be painted at this point with a primer and topcoat. You may want to go back and contact the supplier to see if they have any other suggestions.
Ken Buchinger
NCI Building Systems, Inc.
5/9/2011
It looks like burnishing of the Galvalume coating. Burnishing will not affect the performance of the roof but you do have the aesthetic issue. Unfortunately, there is no way to remove black burnish marks.
Karen Shane
5/10/2011
Thank you for your help. I have the metal supplier coming out to have a look and to see the product that I used on the roof and he will be speaking with the company that did the coating. Is it true that the paint costs $400 a gallon? Yikes!
Todd Miller
Classic Products, Inc.
5/10/2011
If you wnat to use an air-dry Kynar, yes a cost in that range is expected. However, you can also go to quality name brand paint store and use the primer and top coat they recommed for something like this and get by for far less cost. The chalk and fade resistance will not be as good as the air-dry Kynar though.
Karen Shane
5/10/2011
Burnishing sounds right as I notice that the area that has dark streaks is also very shiny. I expect this to be a very expensive mistake on my part... Thanks for your help.

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