Saturate a soft cloth with white vinegar. Wipe down the rusty areas of the patio furniture with the cloth, re-soaking it in vinegar as necessary. Allow the vinegar to penetrate the metal for around 10 minutes. Rinse it off with a garden hose.
Fill a bucket with 1 gallon of water. Add 1/4 cup mild detergent. Dip a scrub brush in the mixture and scrub down each piece. Spray the furniture with a garden hose and pat it dry with towels.
Put on a pair of goggles and attach a metal wire brush to a handheld rotary tool. Run the rotating wire brush all around the metal patio furniture. This will remove the rust and properly expose all the holes you need to fill. Wipe down each piece of furniture with a tack cloth when finished.
Squeeze out a silver-dollar sized amount of autobody filler and swab it on each hole with a putty knife. Give it 10 minutes to harden.
Sand down the surface where the holes were with a 200-grit sanding block and then follow with a 300-grit sanding block. Wipe down each surface with a tack cloth. Your furniture is now ready for more refinishing.