All of this is pretty much the same for any other acid based product. I would not recommend using this product over concrete or blacktop or for that matter any surface you care about. I did this on a limestone gravel pad at my cottage. I sprayed it on, let it sit for about 5 minutes then used a brush on a handle and some soapy water to scrub/rinse it off. I used a garden sprayer to apply it to the bottom of the boat which may be why I needed the respirator. I used elbow length rubber gloves and grabbed a respirator mask after about a quarter of the way into the project.
I used a product called Zing and both came out like new. They were both absolutes awful to look at. I've bought a couple flip boats over the years that sat in the water for several seasons without thorough cleaning.
