Oxalic Acid and Effluence?

Last week I had a customer use oxalic acid to remove iron stains from his brick foundation while my team and I cleaned his deck, house, and roof. When we got around to that side of the house, there was a white film on the brick where he had sprayed the oxalic. Now I’ve cleaned MANY brick with oxalic, and I’d never seen anything like this. I fired up my new 8GPM Pressure Pro and when the brick dried, the film was still there. Returned today and sprayed it with 50% muriatic solution, brushed lightly, and cranked up the PPPW, rinsed, and that’s the last of that nasty effluence.

Has anyone else ever experienced that?


I know efflorescence/calcium can leach back out after an acid wash. F9 efflo and muriatic acid both can open up the pores enough to let more out. It can happen after initially cleaning efflorescence off. Just got to keep hitting with acid until it’s all out. Someone either here or the FB group had an entire side of an office building that had to be hit about 3 or 4 times before it all came out.

1 Like