How do you prep metal patio chairs with rust to repainted them???

Sand them

knock off all loose material, start sanding with a metal grade sandpaper. If you can’t get it painted in the same day with a stain blocking primer put just a touch oil chapstick et ceton the newly sanded areas ..wash off before painting.

If it's light rust, Naval Jelly works pretty well. Otherwise, sandblast them.

I used a thin putty knife to scrape under flaking paint to chip off large pieces on newspaper to clean up. Then scrub with a wire brush until it stops coming off. Wipe down with a clean cloth or spray with air. I removed plastic arm tests with a screw driver. Use rustoleum paint and use at least two light coats. When dry replace plastic pieces, if you have any.

Sand first :)

Any other suggestions??