Those are acid rain stains for sure. Apply SH at 4.5% and let it dwell for 20 minutes. Repeat 2-4 times without rinsing, then wash it. Post treat with vinegar.
Vinegar will neutralize the SH, but does it have any other effect on this stains themselves?
Why would you post treat with vinegar?
@Diamond_Soft_Wash @CFH it was a joke.
In all seriousness, it looks like some warm out or poorly laid concrete.
I tried some rust remover and oxide remover in a small corner today; no success. I scheduled a roof wash for later in the month if anyone has any real advice it would be appreciated.
It is just really old decorative concrete. Wash it there nothing you “the cleaning industry” can do to make it look better. I have a concrete guy I refer after cleaning if they want it redone.
I dont think ots decorative I think its poorly done 50/50 mix. Set expectations with customer
Looks like a porch that was finished unevenly. Porches have a slick or trowel finish that is done by hand. Trowel finishing will dry darker than a broom finish depending on the finisher. The more it’s troweled, the darker it gets. Old school finishers would trowel concrete until it was almost black.