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Tech-ox A patina for bronze


I used to purchase a chemical patina (Tech-ox “A”) for bronze that
turned the metal black. This wasn’t paint, but liquid that soaked
into the pores of the bronze, giving it a very consistent finish
without any build-up. I just found that Technic no longer makes it.
Does anyone out there know of a chemical that will work?

Many thanks,
Jeff Herman

The Colouring, Bronzing and Patination of Metals, by Richard Hughes
and Michael Rowe, has some 18 formulas for producing dark gray to
black patinas on bronze. It’s available on Amazon, both new and used.

Elliot Nesterman

Don’t know if the same chemistry is being used but Birchwood-Casey
makes some selenic acid black and brown patinas that are variable in
darkness (concentration and time) and are both very good at handling
ware. Problem is it is difficult to find repackaged as B-C sells it
by the 5 gallons (about$6-700.00). Sculpt Nouveau

may have it in smaller quantities or something equivalent. The folks
there are great and VERY helpful!!!

John Dach

My favorite treatment to produce a black patina on bronze, brass,
copper and even silver involves the use of selenium dioxide solution.
This is a material that is used by gunsmiths and others in industry
to blacken a variety of metals. It is commonly used to produce or
repair the “blue” finish on firearms. I use it on castings of
Si-bronze sculpture to produce a range of shades ranging from grey
through brown to jet black. It can be bought at places such as
sporting goods stores, Walmart (sometimes), gun dealers orgunsmiths.
The last I bought was made by Birchwood Laboratories, Inc. and
marketed as “Brass Black” in a plastic bottle containing three fluid
oz. (90 ml). This amount will cover a lot of surface. Expect to pay
about $5.00 in the USA. If a single coating doesn’t give a dark
enough color, put additional coatings on. It must be applied to clean
metal! There may be some color variation depending upon alloy
composition but this is true of most any chemical patina. On silicon
bronze it is very good and black. On sterling silver it produces a
dark brown to black patina. The patina coating binds covalently and
is quite durable. It is best to coat the final product with a good
hard wax (carnuba or some other) as is wise with any patina that you
wish to stabilize.

It must be noted that selenium dioxide and selenous acid are toxic
and should not be ingested. I am careful to keep it off my skin.
Knowing my own bad habits, I generally wear rubber gloves when using
this and most of the other solutions I use for patination.

I hope it works for you. Gerald Vaughan

Hi Jeff,

Rio Grande has a couple of bottled liquid patina solutions that are
formulated for copper alloys, such as bronze. One produces
reddish-browns, and the other produces shades of black. I think they
have names such as “Rio Patina #1” and “Rio Patina #2”. (If you can’t
find them, contact me off-line.)

I have used these patinas on some of the pieces that I have installed
in synagogues. I have found them to be easy to use, providing
consistent, lovely colors----full strength, or diluted.


Hello Gerald,

Thank you for your reply. I spoke to a chemist at Birchwood who told
me that their patinas would act the same wax as the Jax: leave a
built-up film on the surface. I will be receiving some in-house-made
samples from Sculpt Nouveau

a company that supplies patinas. They apparently know what I’m
looking for. I don’t want to end up with more patina on my paper
towel than on the piece itself.

Thanks again,
Jeff Herman