I use a couple different grades of sand, depending on the project. Most are pretty fine. I have a 60 gal, 8 hp compressor, and a small blaster from Sears. It uses all the air that compressor can make, and I still have to take breaks to let it refill. Also, with the heat here in South Texas, I put a large shop fan facing the tank, it gets too hot to touch with bare hand after a couple hours of constant running. I shoot in the drive way, then sweep the sand into the middle, sift it, and use it again. Eventually, it becomes just a dust and floats away. The rest, I scoop up and dump it in the empty lot... The neighbors LOVE it when I pull out the blaster... :evilsmile They run their cars as far down the street as possible and park until I get done
Baking soda in a power washer will take off pretty much anything without hurting the parent material. I haven't seen this in person, but there's no reason it shouldn't work.
