galvanized steel before and after rusting

How to Rust Galvanized Steel

Many of the rusty looking assemblage elements that I add to my art actually start out as clean pieces of metal. I love to incorporate tie plates and nail plates that are used in construction, but in most cases this type of steel has a galvanized finish to prevent them from rusting. Through a variety of experiments, I’ve come to learn a pretty consistent process for removing this galvanization and making the metal rust. It’s an easy method to follow, albeit the first part of the process can be toxic… So be careful if you try this!

Here is what you’ll need

  • Galvanized steel
  • Tray or some other type of container
  • Muriatic Acid
  • Baking Soda
  • Salt
  • Hydrogen Peroxide
  • Vinegar
  • Water
  • Spray bottle
  • Latex gloves
  • Eye protection
  • And the Sun

Making sure you’re wearing gloves, eye protection, and are doing this outside in a well ventilated area, add the steel plates to the tray and pour enough Muriatic Acid to cover their surface. I’ve also had some success applying it with a spray bottle. The reaction the acid has to the Zinc coating will be immediate and will give off hydrogen gas. Don’t stand near this or breathe it in.

muriatic acid reaction galvanized steel

I usually let it sit for 15-20 minutes or at least until the chemical reaction has subsided. Sometimes I’ll agitate the tray a little to ensure the acid is fully in contact with all the surfaces of the metal.

When I feel that it’s been long enough I’ll add water and baking soda to the tray to neutralize the acid and make it easier to dispose of the solution. Make sure to rinse off the steel thoroughly.

Neutralize the acid with water and baking soda

Next comes the rusting solution. I add 2oz. of salt into a spray bottle with 8oz. of hydrogen peroxide and 12oz. vinegar. Shake it well so the salt is completely absorbed.

Rusting solution for metal

Begin spraying this solution on the steel. If you have successfully removed the galvanization you should start to see an immediate reaction with the steel. I usually spray this and get things coated well and then just let it sit in the sun.

After about a half hour of sitting in the sun the first spraying should be dry. You should also start to see some significant changes to the patina of the steel. I repeat this process a few more times, making sure to agitate the tray and flipping the pieces over to get both sides.

For the last spraying I’ll just let the metal soak in the solution and forget about it for a few hours. If all goes well, I’m usually left with a very rusty looking patina covering both sides of the steel. Wait another 24 hours and it will change a bit more.

tray of galvanized steel rusting in the sun

The last step in all of this typically comes when I’ve completed one of my assemblages, and that is to give the steel a good clear coat. I typically do this with a polyurethane or a varnish. It helps to protect the rusted patina and also keep air from getting to the steel, stopping the potential for any future rusting.

 

 

How to rust galvanized steel