Why a rust blue takes the passes it takes

Slow rust bluing is the slowest finish on the price list. It is also the one people most often ask to have done by next Friday. It can’t be, and the reason is worth understanding, because it is the same reason most good work takes the time it does.

Bluing is rust

There are two kinds of rust that matter here. Red rust is the kind that ruins a gun: loose, flaky and hungry. It keeps eating. Black oxide is its well-behaved relative: thin, hard and stable. It does not sit on the steel like paint. It is the surface of the steel itself, changed.

Every true bluing, hot or slow, is a way of getting the black kind and not the red kind. (Cold blue from a bottle is a different thing, a touch-up and no more.) Rust bluing does it in the most direct way there is. You make red rust on purpose, and then you convert it.

One pass

1. Polish. By hand, with stones and paper on a backing block, so flats stay flat and lettering stays sharp. This is where most of the hours go. Bluing hides nothing. Every scratch you leave will still be there, only black.
2. Degrease. Completely. A fingerprint will show in the finished work.
3. Apply the solution. A thin, even coat, wiped on. Too much and it runs and leaves streaks.
4. Wait. The steel is left to rust. This takes hours, and how many depends on the warmth and the damp in the air. What you want is a fine, even coat of red-brown rust, like a peach’s fuzz.
5. Boil. The parts go into boiling distilled or rain water. Hard tap water, and Hill Country water is hard, leaves spots. Within minutes the red turns black.
6. Card. The loose black velvet is rubbed off with degreased fine steel wool or a slow, soft carding wheel. Underneath, the steel is a little grayer than it was.

That is one pass. After one pass it does not look like much.

Why it takes many

Each pass converts a very thin layer, so the color has to be built. Gray, then a darker gray, then a deep satin black. A good job is commonly six to ten passes. Some steels take the color quickly and some fight it, and the steel decides, not the calendar.

You cannot do two passes in an afternoon by trying harder. If you rush the rusting, the coat is thin and patchy. If you leave it too long, the rust bites in and pits the surface you spent days polishing. So the work goes at about a pass a day, and the weeks add up. After the last pass the steel is oiled and left to rest for a day before it is handled.

Most of that time nobody is touching the gun. That is not idleness. It is the part of the job the steel does.

Why not hot blue it

Hot bluing is quicker. The parts go into a bath of hot caustic salts and come out black in well under an hour. It is a good finish, it costs less, and on most modern rifles it is the right choice.

It is the wrong choice for many double guns. Their barrels and ribs are often joined with soft solder, and hot bluing salts attack it. A double that goes into the salts can come out in pieces, sooner or later. Rust bluing does not do that.

It also looks different: a softer, satin black, the finish many older sporting rifles left their makers with. If you are putting an old gun back the way it was, that matters.

A ceramic coating is tougher than either against sweat and rain. It also looks like neither. None of the three is wrong. It depends on the gun and on how you use it.

What you are paying for

Not the solution, which costs very little. You are paying for the polishing, and for someone to come back to the same parts day after day and do the same careful thing each time without skipping one.

Good work takes the passes it takes.

Looking after it

Blued steel is still steel. After you handle it, wipe it down with a lightly oiled cloth. After a wet day, dry it, oil it, and leave it out of its case overnight. Done right and looked after, a rust blue will outlast you.