Strip rust from tools, hardware, and outdoor metal using mechanical scrubbing and an acid soak, then protect the bare metal.
Put on safety glasses and gloves, then scrub the surface rust away with a wire brush, steel wool, or coarse sandpaper (80–120 grit). Removing the flaky top layer lets the next step reach the metal underneath. Work outdoors or in a ventilated area to avoid breathing rust dust.
Submerge the metal item fully in plain white vinegar and let it sit for several hours to overnight, depending on how heavy the rust is. The acetic acid dissolves the iron oxide. For items too large to submerge, soak a cloth in vinegar and wrap it tightly around the rusted area.
Pull the item out and scrub with steel wool or a brush. The rust should now wipe off as a dark paste. For stubborn spots, make a paste of baking soda and water, apply it, and scrub again. The baking soda also neutralizes the leftover acid.
Rinse with clean water and dry the metal completely with a towel — bare, freshly cleaned metal flash-rusts fast if any moisture remains. Immediately apply a thin coat of oil (for tools), primer and paint, or a rust-inhibiting spray to seal the surface and stop it from rusting again.