Heat colouring mild steel

Jewelry Discussion
1

Hello All

I was wondering if there is anyone out there, who can give me some
advice on getting a uniform black finish on mild steel. I’ve seen
examples that have been achieved with heat, and they are really a
dark charcoal black on what I’m pretty sure is a sandblasted
surface. With a torch I have never been able to achieve it and I was
wondering if you would need to use a kiln?

I have heard about putting pieces in hot oil but not sure how to do
this.

I would most appreciate any suggestions from all you incredibly
knowledgeable folk!

Christel

I apologise if this is a repeat thread. The prospect of trawling
through all the archives was too much to bear!

2

Use an electric kiln, uniformity of color is difficult with a torch
as the burning fuel reacts with the steel. The work must be clean,
clean, clean for uniform results.

James Binnion
James Binnion Metal Arts

3

Hi Christel,

I just recently asked a similar question and received many helpful
posts. Search Blackening Steel and follow the thread to read all of
the responses. You may also want to take a look at YouTube for
videos.

Pam Farren
Newburyport, MA

4 
I was wondering if there is anyone out there, who can give me some
advice on getting a uniform black finish on mild steel.

Raw linseed oil is nice. Heat to cherry and dump your metal in. I’ve
had success with it.

Regards Charles

5

For a quick, cheap method, get your steel red hot then dunk it into
transmission fluid.

In a closable metal tin, as the oil may well catch light.

6

Hi Christel,

I have heard about putting pieces in hot oil but not sure how to
do this.

There are a couple of different methods of getting a nice black.
Heating with a torch until the metal goes past blue will give a deep
gray/black. It’s the finishing material that brings out the deep
black. I’ve used old motor oil, shortening, and inexpensive vegetable
oil and achieved blacks with each. As you begin to heat the steel,
start applying the oil thinly with a rag or spray it or use an
inexpensive boar bristle paint brush. It’ll smoke, so have some good
ventilation. As the oil starts to heat, it’ll get thick and change to
a deep golden color, then to brown, and finally to black. There’s a
fine point where it’s black and when it starts to burn off. It may
take you a few layers of heating and oil to build up a nice even rick
deep black. Just like with a cast iron skillet on the stove.

Another finishing method is to get the steel heated to the deep gray/
black. Let it cool, and then spray with a clear acrylic lacquer. It
comes in a gloss, satin or matte. Experiment with the thickness or
number of layers.

Have fun!
Valerie

7 
For a quick, cheap method, get your steel red hot then dunk it
into transmission fluid. In a closable metal tin, as the oil may
well catch light.

Don’t do this, there are toxic fumes generated by the decomposition
of the ATF in this process and ATF is very flammable.

James Binnion
James Binnion Metal Arts

8

OK, there is a short cut. Our Antique Patina liquid, no heat, turns
steel black. I did some shop tools years ago and they have held the
color well. Bill

Bill, Deborah, Michele & Sharon

9

I second the linseed oil- the only diference is I put a pound of
beeswax in the pot to add a coating to the steel that is black. if
the piece is going to be brassed or selectively polished the wax also
will preserve some of the finish- I use a BBQ brush- melt the wax/oil
together and brush it on and quickly use an old t-shirt to wipe the
excess- thin sheen of wax- dark coat of oil- stores nice and feels
good in the hand.

10 
For a quick, cheap method, get your steel red hot then dunk it
into transmission fluid. In a closable metal tin, as the oil may
well catch light.

The oil will only catch if the hot metal is exposed to air, and
usually only the oil in the metal.

You have to get the oil really high to hit the flash point if you
are dealing with enough oil to quench and colour any steel.

I have a trash can full of a non-synthetic motor oil. If I heat up a
piece of steel, and plunge it into the oil threr will be a lot of
white smoke.

However if I lif the hot steel out before it has sufficiently cooled
the oil on the steel will flash, and you will lose hair.

Regards Charles