Thread: Black steel

Oh no that's not what I meant.

I've etched with ferric, hot vinegar, lemon juice, mustard. I like the gel of naval jelly best. Another tip i learned is to add ivory dish soap to break the surface tension to avoid splotches. the DD I was whining about looked like it needed some artificial aging so i etched the whole blade with jelly.

As soon as I saw the hammering on the tang I knew what I wanted to do with the imp... I thought it was an original idea,lol since then I've seen one or two blued like Chris mentioned which is almost the same thing. Mine will be black

Some pattern welded blades are treated with gun bluing after etching and polishing to darken the deeper etched lines. This also converts the oxides left there into a more durable form that rusts less. That is the point of pre-rusting a barrel with a bluing process.

Old timey browning is the same process, but one critical part is left out. If you want a dark blue/black, boil the rusted and treated part and the oxide will turn very dark. Boiling water is not hot enough to ruin any heat treatment and has been used as a sterilizing technique anyway. If you still want some of the shiny lines, merely rub lightly with a very fine paper or scotchbrite to bring out the highlights again.

From the book Home Machinist's Handbook:

"Black Finish for Steel Parts: The following method can be used to provide a jet black, rust-inhibiting finish on any steel part. This finish looks especially nice on nuts, bolts, and screws used in small mechanical assemblies. To obtain the finish, simply coat the part with motor oil and place it in an oven or a hot plate. Heat it to approximately 350ºF. The oil will bake into the part in about 10 minutes, leaving a hard, durable black finish."

This works great.

Matt

Originally Posted by Smiles

From the book Home Machinist's Handbook: "Black Finish for Steel Parts: The following method can be used to provide a jet black, rust-inhibiting finish on any steel part. This finish looks especially nice on nuts, bolts, and screws used in small mechanical assemblies. To obtain the finish, simply coat the part with motor oil and place it in an oven or a hot plate. Heat it to approximately 350ºF. The oil will bake into the part in about 10 minutes, leaving a hard, durable black finish."

And a good method. Needs to be done with care so as to not overshoot the temperature and ruin the hardness of the steel. That's nearing the top of the range for tempering temperatures. Baking the oil onto the surface means you won't be able to follow any color changes to avoid overshooting.

A variation on this theme is to heat the metal and then rub beeswax onto the surface. It'll melt and smoke a bit. More of an organic petroleum...smells good too.

I've done both kinds of finishing on black irons that are going to be exposed to weather. it lasts about two years and can then be repeated. I've never done this to a knife or edged tool. Hmm, something for the experiment list.

=-O Smiles! That sounds so easy! I assume you've tried it? I think that when i decide to rescale a razor (plastic scales would melt) i will do this...perhaps to my wapi which i just realized is all metal scales and all. I am intrigued. do you have more information smiles?

edit: perhaps i will let someone else try it first haha...

Originally Posted by Detach

=-O Smiles! That sounds so easy! I assume you've tried it?

Not yet. I ran across it at the same time a fellow I know needed to blacken car suspension bolts and nuts and so on. He did it and it worked great. The nice part was that, unlike some other finishes or patinas, there was no appreciable coating, so the fasteners' threads worked fine.

I plan to try it sometime when I rescale, too.

I wouldn't worry about a 350 heat doing much negatively to temper.

Originally Posted by Smiles

Not yet. I ran across it at the same time a fellow I know needed to blacken car suspension bolts and nuts and so on. ...

I wouldn't worry about a 350 heat doing much negatively to temper.

For nuts and bolts probably not. But unless we know the exact steel in a razor, it might be cause for just a little worry. I do my tempering in a Paragon HT furnace that has about a 5 degree cycle around a set point or a low temperature salt bath that might cycle 25 degrees below a set point without any overshoot. Someone doing a 350 temper in a home oven could have as much as a 50 degree cycle, maybe more, and then even the placement in the oven can have effects. The margin of error is something to attend to.

Otherwise take less chance and use the chemicals.

I'll bet that this process would work without going to 350 degrees. Maybe start at a safer 250 degrees or so. Otherwise this is a great idea, and I suspect I'll be giving it a try sometime...

Josh

Originally Posted by JoshEarl

I'll bet that this process would work without going to 350 degrees. Maybe start at a safer 250 degrees or so. Otherwise this is a great idea, and I suspect I'll be giving it a try sometime...

Josh

I don't know, it looks like the same thing one does to season cast iron cookware, but with motor oil instead of vegitable oil.

I am not sure you would get the same chemistry in the oil at the lower temperatures.