Blackening for steel work

[stretch]

I am looking for blackening liquids for my metalwork. I know of birchwood casey and contacted them, I am wondering if there are any others.

[HWooldridge]

Birchwood Casey makes most of the hot and cold black agents for other retail distributors - like Brownell's. I use Oxpho and it works quite well.

You can also brown it (rust) to the point of almost being black with brine, hydrogen and peroxide. Search the archives on this site - I asked for recipes about a year ago and the simplest one worked the best.

[james gonzalez]

you could try sculpt nouveau in california.
I know they carry birchwoodcasey and they may know of other options.

[Ice Czar]

hydrogen peroxide treatments work best with the steel at a pretty high heat not forge heat mind you but still a black heat, where you can see the water vapor on the steel driven off, we use a propane weed burner.

the easiest cheapest route is stove polish but it may not be at all what you have in mind

it sort of depends on what you mean by blackening and what you mean by steel. A chemical cold blue like what Birchwoodcasey offers is very different than both the above. We buy various Birchwoodcasey bluing solutions and make our own as well (nitric acid, cupric sulfate, selenious acid)

When it comes to "true" bluing (which is often black or dark charcoal) its often a heat treatment with carbon or chemicals, as applied in gunsmithing the processes have changed over time with the carbon content of the steel employed in making the parts, it gets really interesting when you look at some guns that may have up to three different bluing processes employed.

some basics
Bluing (steel - Wikipedia))
Passivation
Nitridization
Carburization
Case Hardening
Restoration Articles - All About Bluing (ARTBLUE.HTML) (good basics of the various processes employed at one point or another)

the bluing most suitable to mild steel, is slow rust bluing, which is highly labor intensive in that you card off all the red iron oxide which is a larger molecule and leave only the black iron oxide which is smaller with a tighter molecular bond, then repeat the process till you get an acceptable finish (which is covered as "RUST BLUING" by Bill Adair in the article above)

there is a great amount of confusion in bluing terminology, with many names describing the same or nearly the same processes, in British parlance substitute "blackening" for "bluing" the actual finish you get depends on the process and the steel that is employed, from a deep black to a temper blue

[Farmer Phil]

Here are the corrected amounts for Dave Vogel's museum wax (interior) finish.

• 1.5 Cups melted beeswax (a little more than 2 cakes like at Ace Hardware)
• 1 Cup turpentine
• 1 Cup linseed oil
• 1 Teaspoon Japanese drier

He suggests combining all liquids then heat them up enough to melt in the wax (no open flames!). But, I melt the wax first and then add the other ingredients. I got all the stuff, including quart paint can and lid for storage of finished product, at Home Depot. Well actually I had the beeswax already.

Apply to 200-300 degree hot metal with a cotton applicator (we roll up old pant legs). It will smoke a bit as it soaks in. Fully cures in a day.

[Bart Trickel]

I use a product from Caswell called Black Oxide.
Caswell Inc. - Black Oxide Kit
It works good and fast, low toxicity I think also.
A bit expensive but a little goes a long way.

[steponmebbbboom]

perhaps i am being naive.

But for blackening forged steel all i do is heat the steel until it is too hot to touch, not glowing, just before colours start to run. then i wipe it down with a rag soaked in vegetable oil. just regular vegetable oil. this instantly turns the steel black.

its not like paint but it holds up ok outside.

[tzonoqua]

no you aren't being naive...

you can use vegetable oil

I use a mixture of meths or turpentine, tannic acid and a drop of oil. apply with brush when hot. gives a matt rich black/brown finish. Or sometimes I use just oil, or another favourite is 'jacobean' briwax. Only suitable for indoor uses. After a while outdoors it will eventually rust.

For outdoors I use paint, generally. Or if it's something like a big gate or railing that someone has spent a lot of money on, I send it away to be galvinized then powder coated.

Colleen

[ThomasPowers]

Boil it in strong tea ---tannic acid will blacken the surface; but you will still need to protect that from rusting.

[GOATMAN]

I hit the steel with a wire wheel on the angle grinder when it's red hot - knocks of any scale instantly, smoothes the surface beautifully, and because the metal is hot, it immediately returns to a shiny black. This works with a hand wire brush and elbow grease, too. Then just wax or linseed oil, or the clear coat of your choice, to prevent rust
It's not really suitable for hard-to-reach surfaces, though, but this adds contrast and depth to the work, high surfaces shiny and black, low spots dark grey matt.

Obviously, this doesn’t work with anything that is heat-treated and then polished. Also, when you work the wire wheel over hot steel, it’s really aggressive, and you have to be careful. You quickly loose hard edges, and even smear your touch mark!