rusting steel

Does anyone know what could be used on steel to give it an instant rusted finish? A friend of mine said there is some chemical that is used but he wasn’t sure what it was called.

There are a few ways to rust steel in a controlled way.

Disclaimer: While I have tried all of these methods, that doesn’t mean you can’t screw them up. Each one is dangerous enough to potentially send you to the emergency room. When in doubt, try a small piece with lots of protective gear first to make sure you’ve got the hang of it. And please don’t sue me or Core :slight_smile: I’m just trying to help.

For all of these methods, your piece should be cleaned with a scotchbrite pad and soap, then rinsed. Or, if the surface is super complex, sandblast it. Any oil or gunk on the surface will keep rust from forming, so after you clean it, don’t touch it except with paper or cotton gloves, or something. You can use this to your advantage by applying nail polish or clear coat as a resist to keep parts from being rusted.

1) If the piece is small enough, make a tub of water with a solution of one heaping spoon washing soda to two liters of water. Get a lantern battery, and two wire leads with alligator clips on the ends. Clip the negative terminal of the battery to the workpiece to be rusted. Clip the positive terminal of the battery to a sheet of stainless steel, preferably larger than the piece to be rusted. Leave this overnight. Depending on the current from your battery, you will have some rusting in the morning. Leaving it longer will rust it further. Be sure to suspend the object to be rusted using non-metallic string, so that rusting is even. Also, the setup may produce fumes, so you’re better off doing it outside, or in a well ventilated shop. DO NOT use AC current. Not only will it not work, but you will probably get shocked.

2) If the piece is too large for method one, you can use fuming muriatic acid (hydrochloric acid solution used for cleaning calcium deposits on driveways and concrete walls). This method requires you to heat up a strong acid. Please check out this site for acid safety tips first:

http://www.ee.byu.edu/cleanroom/acid_safety.phtml

So, now that you’ve got your safety gear on, place a few cups of acid in a pyrex bowl that is nested in a larger pyrex bowl of boiling water. Place the piece to be rusted next to the bowls and cover the whole shebang with a trashbag. Come back in a day or so and see what it looks like. This will produce a very uniform, fine rust on the surface of the sheet. If the fuming is too much trouble, the acid may be applied with a brush, but the rusting will not be as even. Be sure to neutralize this acid with a baking soda/water solution before doing anything with it. See below for finishing of the piece. Be very careful not to drip water into the acid, as it may spatter. Wear eye protection AT ALL TIMES. And do this outside. These are acid fumes, which nobody likes breathing, and which will rust all steel in your shop!

3) If the piece is too large for method one or two, then try the following. Prepare a solution of hot white vinegar with as much salt dissolved as you can. Preparer a lot, since we have to coat the entire surface. Put some of the vinegar solution in a spray bottle and spray it onto the surface of the metal. After you have covered the surface, cover the piece with a plastic drop sheet to keep the piece from drying out. The hotter the metal is, the faster the rusting will occur, so if it’s in the sun, or if you can run a torch or fire behind it, you will be done quicker. If the surface begins to dry, spray more solution on.

Finishing:
All the pieces should be washed thoroughly, and sealed against further rusting (unless you want more) with clearcoat or another oil-based sealer. The acid methods should be washed first with a baking soda/water solution to neutralize any acid. If the workpiece is not washed well enough, oxidation will continue as long as there is oxygen, and will probably eat right through the piece (especially if it is sheet material)

I hope this helps. Method three is probably the easiest, but it’s results won’t be as even as one or two. I would start with three and see how it looks. If that doesn’t work, twoB (brushed on acid) is the next easiest, but it might even be more non-uniform. In my opinion, fumed muriatic will look the best. There are definitely more ways to do this, and there is probably even a kit available at craft stores. But, if you want to use commonly available stuff, these ways work pretty well. Just be careful out there.

I’ve seen some science demonstrations (on TV)
Where a bit of water and salt and some electricity(to sped up the process) covered the whole nail (in a glass) in rust crystals(FeO2). overnight… not INSTANT, but acceptable.
I’d go to a science board for more info on this process…