Here are some photos, before and after, of rust stain removal on an aggregate patio. We used two applications of F9 BARC to remove about 95% of the staining. The customer was very pleased with the results.
Total cost of materials: $45
Total labor time: 2 hours
Charge for service: $285
we washed it with a 3 gal sh to 2 gal water + 16 oz. simple cherry mix, downstreamed 10:1, surface washer, ball valve rinse.
used a dilution of 2:1 water to F9, applied light to each section, heavy on the rust spots… dwelled for about an hour till dry, rinsed with water to reactivate, broomed, then complete rinse. repeated that process again and it was all good. about 95% stain removal.