Bluing steel with heat & oil

A buddy of mine (we are both in the SCA) has a mild steel helmet that we are rebuilding. The helm was blued years ago by heating it with a mapp gas torch and dunking it in motor oil, but because of the uneven nature of the heating process, the bluing is unequally applied. We would like to re-do the whole thing in a more evenly distributed fashion, but I have only ever seen this done once.

So a couple questions:

  • Does anyone have experience with this process who can provide guidance?
  • I hear that the metal shop has an oven/furnace that is large enough for the helm pieces (see photo), is this the case?

Thanks in advance!

There is a furnace large enough for it and would get it hot enough. But oil quenching I don’t believe is permitted due to fire hazard.

Mitigating the fire hazard - could the quenching be done out in the rear parking lot? (with the next problem to solve being - how to safely/quickly get the hot metal from the oven to the oil, heh).

Or, is there a different medium that we could use that both adds the layer of protection and hopefully replicates the effect on the steel?

I think it would cool too much to cover that distance, that is thin metal. You wouldn’t want to be running through the shop with red hot metal.

IF it is possible to move furnace over to loading dock you could, heat it up, open the door and get it into the quench on the ground.

@Team_Metal_Shop can the furnace be moved to the loading dock? If there power for it over there?

Ok, lots going on here. First, it doesn’t sound like “bluing” was ever involved here. That’s a pretty specific process that only has 5 or 6 ways to do it and all of 'em are pretty specific. From your description, this sounds like blackening with motor oil- a process really similar to one that we in blacksmithing do all the time (we usually use linseed oil, but it’s pretty flexible).

On moving an oven close to the doors for a “quench” outside- prolly not gonna work because one oven is crazy huge and the other’s controller was having surgery last I saw it (on Saturday). They both run on 3-phase power and if that’s available near the loading dock, I don’t know about it (but I’m not saying it isn’t).

The good news is that it probably isn’t necessary. To get a good black, the metal really doesn’t need to be that hot, and you don’t need to quench all at once. It’s doable wit a torch and you can build it up in layers, sand/polish, all kinds of stuff until it looks like you want- and like I say, I think linseed oil is gonna do you much better than old motor oil.

I’m teaching induction forge tomorrow night if you want to chat about it. The class is at 7, I’ll be at the space a little before and for a while after.

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Cool, thanks for the information! I will try and be up there ~6:30 or so.

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I use a 1:1 mix of beeswax and boiled linseed oil as a blacksmithing finish. Heat metal to black hot (hot but not so hot as to glow) then dip or paint on with a natural bristle brush (synthetic will melt). I just let it air cool - no quenching needed unless you’re in a hurry to wear it. Mild steel won’t harden (not enough carbon), so quenching won’t help with that anyway.

I’m showing a camp tripod I made as a handy example of the finish. Working in sections is fine; I heated these rods up in three heats to get them finished from end to end.

The end result is similar to the “seasoning” one puts on cast iron. Note that because of the boiled linseed oil, this is NOT considered a food-safe finish (not much of an issue for your armor, but…)

Here is an example of the finish. I treated this metal back in March and it’s been riding around in the back of my pickup, exposed to the elements for about four months. There’s only a couple of minor rust spots where the finish was abraded away.

If you hit the treated metal with a little oil, it’ll shine up a bit, too. I used PAM here: any light oil will do (canola, peanut, Crisco, et al). Use something from the kitchen, not the garage. Avoid the butter-flavored PAM unless you want to smell like popcorn on the battlefield.

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Sir you armor smells like pancakes!

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Have at you, Sir Butterball!

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