How to rust sheet metal
We've looked at corrugated sheet metal as a material for interior decor, and it has just as many uses outdoors. But if you really want to create a rustic setting you might want to encourage sheet metal to rust. After some research I undercovered a few tips and tricks on how to rust sheet metal quickly...
Hydrogen peroxide (available at pharmacies)
Goggles and gloves
It's important to wear proper safety gear when working with acids, so make sure you have safety goggles and rubber gloves. You are ultimately responsible for using this information in a safe, conscientious manner and for not using it irresponsibly, as we accept no liability for misuse or lack of safety precautions.
Sheet metal has a protective coating that prevents rust, so this needs to be removed before you can start the rusting process. Any paint stripper can be used to remove the protective layer, which can then be rubbed down with a degreaser. Wear gloves and goggles when using paint stripper - this stuff burns skin! Try to avoid touching the metal with bare hands or you will leave oily fingerprints which might show up on the final finish.
You can see left, I simply hung up the degreased object and sprayed it, but you can see where the solution did not penetrate or rust.
To remedy this I pickled the metal. You can pickle metal with the same ingredient that is used to pickle - vinegar! Place the object where you can spray it from all sides, away from anything you don't want to get sprayed.
Put on your safety goggles and gloves. Put some vinegar in a spray bottle. Not too much - just enough to cover the object several times. Spray the object from top to bottom all around. Soak it good. Let dry and repeat several times. The more the better. Placing the object in direct sunlight will speed drying. The acid in the vinegar will etch the surface of the metal so chemicals can penetrate. If you skip this step and proceed with the next step or don't like the results of the next step, just come back to this step and spray again with vinegar. The acid in the vinegar will dissolve most of the rust. Don't worry about it. This is normal.
Wearing safety goggles and gloves, mix up a batch of rust accelerator, adding ingredients in the order given:
450ml Hydrogen Peroxide
60ml White vinegar
1/2 Tbsp Salt
Mix in a measuring cup, making sure to dissolve the salt. Transfer into the spray bottle with a funnel. Tighten the spray bottle cap and shake well to dissolve the salt.
Spray the solution onto your object, soaking it from top to bottom all around. Now sit back and watch the magical transformation. It will start foaming and begin to rust before your eyes. If it doesn't rust then you didn't degrease it enough or you didn't pickle it enough and will have to repeat one or both of those steps. The rust patina will deepen each time you repeat the spraying and drying cycle up to a point beyond which there is no noticeable change. Keep spraying and drying until you are satisfied with the degree of rusting. I repeated the cycle about 6 or 7 times.
You will be using an acid, vinegar, and an oxidizer, hydrogen peroxide, so do wear the safety goggles and gloves. Be careful where you spray the solution. It is mildly corrosive and will rust anything made of iron or steel. Do this outdoors preferably in a place sheltered from the wind and away from people or pets. Do use common sense and follow common safety practices. Do not spray chemicals at anything other than the object you are trying to rust. Obviously don't spray it anywhere near people or animals. Don't breathe the vapours. Although the chemicals used are relatively safe, common sense should prevail.