How to Remove Rust from Cast Iron

Pull together the rusty cast iron pan, baking soda, water, white vinegar, a high-smoke-point oil like avocado or grapeseed, kosher salt, a stainless steel chainmail scrubber, and paper towels.

The whole process takes about 3 hours including oven time. Active scrubbing and prep is around 15 minutes; the rest is the oven cycles.

Spoon a few tablespoons of baking soda directly into the pan, then add just enough water to form a thick paste. Use less water for heavier rust (you want it more like wet sand), more water for light rust.

The paste is what physically lifts the rust off the iron. Baking soda is mildly abrasive without being harsh enough to gouge the surface.

Scrub every part of the pan with the chainmail scrubber and the baking soda paste. Don't skip the handle, the underside, or the inside corners - rust hides everywhere and any leftover spot will spread.

Apply firm pressure and work in circles. Rinse with water when one section is clean and move on. The water that runs off will be orange-brown - that's the rust coming off.

Make a fresh paste and scrub again if rust remains. For heavily rusted pans this can take two to three rounds.

The pan should look mostly silver-grey with no visible orange or red patches before you move on. Cast iron's natural color is dark grey - any reddish tint means there's still rust hiding.

Pour white vinegar over the pan and rinse. The vinegar neutralizes any leftover baking soda residue, which would otherwise interfere with seasoning.

A quick splash and rinse is all you need - don't soak the pan in vinegar. Long vinegar exposure can pit the iron, which gives you a worse cooking surface than the rust did.

Dry the pan in a 350°F oven for 10 minutes. Cast iron has microscopic pores that hold water, and any water left behind will cause new rust within hours.

Oven-drying gets rid of all the moisture more reliably than a towel ever will. Skipping this step is the most common reason a freshly cleaned cast iron pan rusts again immediately.

Apply a thin coat of high-smoke-point oil to every surface. Avocado, grapeseed, and flaxseed oil all work well. Pour a small amount onto a paper towel and rub it across every surface - inside, outside, handle.

Then take a fresh paper towel and wipe off as much as possible. The coat needs to be very thin, almost invisible. Too much oil pools and turns sticky during baking; not enough is fine, you just need a few cycles.

Bake the oiled pan upside down at 350°F for 1 hour. Place a sheet pan or aluminum foil on the rack below to catch any drips.

The heat polymerizes the oil into a smooth black coating. Let the pan cool in the oven before handling - the iron retains heat for hours and burns are guaranteed if you grab a hot handle.

Repeat the oil-and-bake cycle two to five more times for a deeper seasoning layer. Each cycle adds a thin layer that builds up like coats of paint.

Two cycles gets you cooking-ready. Five cycles gets you a near-nonstick black surface that rivals a brand new pan. After every meal you cook in the restored pan, the seasoning gets darker and more durable - eggs cooked in butter is a great first meal because it adds a nice fat layer.