Simple finish on mild steel

Blueing--------either chemical bath or slow rust. The slow rust process can produce either a blue or brown finish, depending on procedure. Probably the only time that you will actually WANT something to rust!

Color case hardening---a little more involved, but a really pretty finish if you get it right.

Home shop electroplating ?????

Thin clear lacquer 50%, dip the items in it and let dry. Works for brass musical instruments.

Basic blacksmith's finish - get it hot, but not too hot, and apply linseed oil or linseed oil and wax mixed. Not really very durable, but somewhat durable, and probably as good as most of the other methods that will leave any surface texture visible. Burn any rags or towels used with linseed oil, or otherwise take precautions against spontaneous combustion.

Blackening/Blueing. I bought some jelly called "Nu Black". Not very cheap but very good. I always stayed away from blackening (except with heat and old engine oil). But now, every piece of steel has to be black. :-)

Nick

You've gotten some good suggestions here, Zed, but be aware (as several have pointed out) that the thin coatings that offer some rust protection have little wear resistance. Zinc- or iron phosphating will provide rust protection, but they're extremely thin and scratch easily. If you're really going to use these things as key fobs, those coatings won't protect them.

Likewise the lacquer (two-part catalyzed lacquer is available, and it's tougher, but not tough enough). The bluing and browning come in several flavors, which you can generally classify as "hot" and "cold." Hot is brighter and clearer. Cold (cold-rust, that is, not the "cold blue" that's made for repairing scratches on gun barrels) is slightly frosty and somewhat thicker. If you do a multi-coat job of cold-rust bluing, browning, or blackening (all three are available; even purple, if you want it), you'll have a bit more scratch resistance. But not much more, if the fob lives in your pocket with keys or change.

Plating is possible. There are home-plating kits, and a two-layer job, with copper to smooth out the imperfections and nickel on top for brightness, is easy to do at home. It is not cheap, however. While it is much more scratch-resistant than a phosphate or home-brew black-oxide treatment, it is not impervious. If you want to get fancy and you have lots of money, you can put a flash layer of chromium on top of the nickel. This is the way car bumpers were finished in the past (actually, the bottom layer, under the copper, usually was a flash layer of nickel for better adhesion). The cost is for the plating kits, BTW.

If you want a better solution all around, make your next fobs out of stainless steel. It will cost you a fraction of the cost of making them out of mild steel and then plating or coating, except for paint, of course.

-- Ed Huntress

I use duplicolor truck bed spray available almost anywhere (wal-mart) for things that are going outdoors. It's easy to apply and very durable.

I've had good results with the Loctite Extend spray can on either fine rust or on oxidation from red heating. I think it combines a phosphoric acid conversion with a synthetic polymer lacquer. Easy to find at Home Depot or Lowes and easy to apply. Economical for small pieces. For big pieces you can use the phosphoric acid by the gallon sold in the paint department.

POR-15's Colorchrome looks interesting, albeit pricey:

R, Tom Q.

If they're actually going to be carried rather than hang on a peg, nothing at all. The constant friction in your pocket will keep it shiny (did that with a fob of 6:1 maile made from galvanized fence wire for about a decade--the galv. wore off pretty early in the game). --Glenn Lyford