Oxalic acid is a naturally occurring compound in many fruits, vegetables, nuts, and whole grains. While small amounts of oxalic acid are not harmful, this compound can inhibit the absorption of other ...

Q: My concrete sidewalk and driveway have large brown rust stains that I haven’t been able to remove. I tried bleach and a chemical remover to no avail. Can you help? A: Rust stains on concrete seem ...