Charlie Bress wrote:

I was working on the car and noticed a lot of built up corrosion around the
battery terminals. No big deal, right?
I cleaned of the terminals with a wire brush, replaced the bolts and nuts
(this is a top mounted terminal battery) and then I took the hose and
rinsed of the top of the battery.

Now comes the problem. Wherever the run of went there are nice ugly brown
stains. The driveway is poured concrete and my understanding is that it is
"fiber" reinforced.

What is the best way to clean these marks off? Looking at Google for
concrete cleaning I see muriatic (hydrochloric) acid or phosphoric acid.
These tend to be nasty to work with. Is there something else that will work?
The stains look like rust, but C-L-R doesn't seem to touch it. I tried some
full strength. It might have worked a little.

I am not sure it is rust. I don't know what has been put in the concrete.
The driveway does not show rust marks where it is exposed to the weather.


Charlie

Since battery acid is suphuric acid, putting another acid (muriatic acid
aka hydrochloric acid) on the stain doesn't seem to me to be the answer.
You might try a solution of baking soda and water on the stain. Let it
sit overnight before washing off.