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Brown Patina on stainless steel


#1

Any suggestions as to what one might use to get a dark brown patina
on highly polished stainless steel?

Thank you.
Margery Cooper


#2

You could always use heat, heat it to about 200 deg C for a range of
yellows to browns, the higher the temp the browner the colour til you
get to the blues and peacocks at around 300 deg C (IIRC).

These are surface oxides (similar to old style bluing on gun barrels
and such) so are reasonably wear resistant, but will eventually wear
off.

I suppose you might also try chemical gun bluing compounds, but I
think these are more fragile and tend to be blue/black verses brown.
Caveat I haven’t used these, but have used oxide colours when
tempering tools.

Cheers, Thomas Janstrom.
Little Gems.
www.tjlittlegems.com


#3
Any suggestions as to what one might use to get a dark brown patina
on highly polished stainless steel? 

Ferric Nitrate

John Dach


#4
Any suggestions as to what one might use to get a dark brown patina
on highly polished stainless steel? 

Bacon?


#5
You could always use heat, heat it to about 200 deg C for a range
of yellows to browns, the higher the temp the browner the colour
til you get to the blues and peacocks at around 300 deg C (IIRC).
These are surface oxides (similar to old style bluing on gun
barrels and such) so are reasonably wear resistant, but will
eventually wear off. 

The colors and temperatures you mention are for carbon steel. You
will not get oxide colors from stainless at that low a temperature
and may not get them at all depending on the atmosphere you are
heating in (torch, kiln etc) it may just turn black.

Sculptors use heated application of ferric nitrate to get a brown
patina on stainless. It is a nasty job as you must spray the ferric
nitrate solution on the heated metal and continue to heat (with a
torch normally) till you get the right color. The ferric nitrate
fumes are corrosive so you need a respirator and protective clothing
to do it.

Jim

James Binnion
@James_Binnion
James Binnion Metal Arts


360-756-6550


#6

Not to put too fine a point on it, but I have worked with stainless
steel for quite some time*, and have never had a problem producing
the oxide colours. A regular venturi aspirated LPG torch will produce
them every time on all 300 series and most 400 series stainless
steels; I have also had some success with 200 series steels.

BTW brown is by far the more forgiving colour to get the “range” of
temperature that it occurs over just seems larger.

I have found kilns/ovens to be not as repeatable as a torch though,
not sure why, but there you go. It will take a bit of practice to
catch the heat at the right point to prevent over shooting the
desired colour.

Cheers, Thomas Janstrom.
Little Gems.
www.tjlittlegems.com

  • I started my metals career in blacksmithing, moved to knife make,
    then to light foundry work (bronze and aluminum) and now to
    silversmithing etc. All spanning over 20 years…

#7
Not to put too fine a point on it, but I have worked with
stainless steel for quite some time*, and have never had a problem
producing the oxide colours. A regular venturi aspirated LPG torch
will produce them every time on all 300 series and most 400 series
stainless steels; I have also had some success with 200 series
steels. 

I did not say that it would not heat color just not at that temp, at
200C (392 F) stainless will not heat color. Think about it all your
stainless cook ware would be yellow brown if it colored at that low
a temp. Published colors and temperatures in laboratory conditions
(very clean surfaces, one hour at temperature, 20% oxygen) are as
follows:

pale yellow 	290C 554F
straw yellow 	340C 644F
dark yellow 	370C 698F
brown 		390C 734F
purple brown 	420C 788F
dark purple 	450C 842F
blue 		540C 1004F
dark blue 	600C 1112F

Depending on surface finish, oxygen level, exposure time etc. there
may be variations in presence and intensity of color.

And FWIW like yourself I have worked with stainless for more than 20
years. You might look at xpmcorporation.com to see the work I
currently do in stainless.

Jim

James Binnion
@James_Binnion
James Binnion Metal Arts


360-756-6550