How To Rust Metal
- baking soda
- blow torch
- chlorine bleach
- denatured alcohol / paint thinner
- hydrogen peroxide
- muriatic acid
- clear coat (optional)
- wax (optional)
- Clean steel with degreaser (like lacquer thinner or denatured alcohol)
- Remove all mill scale by soaking or spraying with muriatic acid, let sit until mill scale rinses off. Repeat as necessary. If there is no mill scale, rinse once with muriatic for a good etch. NOTE: You can replace this entire step with sandblasting if you have access to the equipment.
- Make sure piece is completely rinsed with clean water.
- Wet down entire piece with chlorine bleach, sprinkle lightly with salt, and allow to sit until it dries. Spray the piece with water, but lightly so the dried salt/bleach mixture doesn’t rinse off. Just wet the surface down. Let sit overnight.
- The next morning, mix up a pint of FRESH hydrogen peroxide (standard 3% stuff found at drug stores) with a tablespoon of muriatic acid. Spray this mixture onto the piece. Allow to dry. Once dry, spray once more with this mixture. Let sit overnight.
- Next morning, rinse completely with clean water, and you should have a decent rust by now. If there are areas that need more rusting, go back to step 5. Once you are happy with this rust, let it sit for a few days, lightly wetting the surface with water whenever it completely dries out. This will help the rust to really “set in” so it’s not just a light surface rust that will brush off.
- Wet the piece with water one last time, sprinkle on baking soda to neutralize any acids left behind. Gently wipe the baking soda around on the piece, which should help clean off any rust that is too loose. Be gentle, though.
- Allow piece to dry, wipe down again with paint thinner to clean of any superficial haze rust on top of the good rust.
- Heat piece with torch, only enough to drive out any water in the metal. Do not over-heat. Only the get metal hot enough so you can still touch it for a second without burning yourself.
- If you are planning on leaving this piece outside to continue to rust, you are done.
- If waxing the piece, do it immediately, while hot, to get wax to really get into the metal. Let cool completely before buffing out, then wax once more.
- If using a clear paint, let metal cool down to the point where you can comfortably leave your hand on the piece. In reality, avoid handling the piece as much as possible until painted. Paint as soon as possible. Once paint has fully cured, you may wax it if you desire.
That’s it. Your results may vary depending on the environment, heat, humidity, and the way you hold your mouth, just like any patination process. I find warm weather with medium humidity to be the best conditions.