You could spend most of the first day scraping off the old paint. If on the first day you only scrape, you must paint the second day, or at least before the next rain.
You can also use diluted, mild detergent.
Scrape off spiraled railings, ornate areas, and areas where one piece is welded to another using a wire brush attachment on a drill, or an “angle grinder” with a wire brush attachment. These are the only good ways to remove the rust. Eye goggles are necessary. Angle grinders are the best tool to remove heavy rust. Scrape out rust and loose paint from the bases of the railings, where they are mounted into the concrete. Water collects here and causes the railings to rust, often badly. [5] X Research source
Sand rough spots with coarse sandpaper, from 40 to 60 grit.
If you don’t finish in one day, apply primer and paint the next day to prevent the bare metal from rusting. Don’t paint before 10:00 AM because the railings could be damp from morning dew.
Many people prefer to use semi-gloss or high-gloss paint for their topcoat. These finishes add a shine to the railings and can make them easier to clean.
