I’m a long-time searcher and reader. Thank you all for the information.
I cleaned a driveway with a rust stain left by a dripping golf cart. I treated with mutiple coats of oxalic acid mixed at more than 1 cup per gallon. The OA was brushed into the concrete after each application, allowed to dwell for 5-10 minutes, and then washed with hot water. The rust stain got 30%-50% lighter.
A few days later I received negative feedback, and I plan to make it right by providing a refund or improving the stain. I did not properly discuss the rust stain before beginning work.
Am I doing something wrong while using OA? I have used it on a few spots here and there, but I have not been impressed overall.
I told the customer that I can use F9, but it is my understanding that I will need to evenly apply it to the entire driveway. If I could spot treat this area, please let me know. I don’t plan to treat the hole driveway with F9 at the original price.
You can use F9 Barc the way Craig explains to use it for this type of stain and either treat the whole pad and charge accordingly or inform the customer that you can spot clean and try to feather out the edges to blend it but it will be brighter in that spot of the drive
Battery acid stains are super tough. According to what I’ve read, you need f9 double eagle to neutralize, then fo barc at full strength 2x (I believe, the cookbook has the exact info in more detail). If you didn’t promise them perfect then let them know there is a probability that that one area MAY be very white compared to the rest.
With the F9 he does rec doing at least the entire section, not the entire drive. But that one’s not that bad. I’d just try spot treating it and tell customer it’s going to be a little lighter. You can blend it in pretty easily.
Hopefully you learned to talk with customer regarding rust stains are not included in basic concrete cleaning.
You don’t need Double Eagle to neutralize. I was using F9 years before he came out with double eagle. Any base soap or degreaser will do.
How do you all typically spot treat with F9 Barc for small rust stains such as those from patio furniture?
Do you spot treat before or after you clean the concrete? I understand this product is supposed to be used on a dry surface, so would it be ok to hit small spots with it before pressure washing?
I sprayed a few small spots with it after washing while the concrete was still wet, and it did nothing. It would be great to save the second trip needed in order to apply it to dry concrete.
@sixsolve clean it first then do the treatment. F9 has a free app now that you can download with all the processes.
I’ve always found that type of work to be somewhat frustrating unless you really set expectations. I hate spot treating it too and at least go joint to joint or just do the whole thing with a rust remover. I’d rather spend my time washing a house or a roof.
And oxalic acid is much much cheaper and can do a decent job sometimes.
@Racer How does that work, Rick? Apply the base -soap or -degreaser and then the BARC F9? If you don’t mind, what would be the process for that? Sodium hydroxide recipe (I have some on hand)? Then the process itself? I have the F9 cookbook, if that would help explain it…?
I generally use BARC Process #2, method B unless a lot of organic growth also. The water when you surface clean will dilute it or I just use my HW mix when I clean after treatment, if I’m cleaning drive anyway. If just a spot or area, the water will dilute it fine. It’s not that strong an acid.
