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Patina problems with copper


#1

Hi All!

I’ve been using Jax brown patina on copper on some embossed pieces.
After applying the patina and then rinsing it in water, I buff the
piece with a cloth and then sand the patina off the high points for
the contrast. I thoroughly rinse the piece in water again. When dry,
I apply Renaissance Wax to seal the copper. My problem is that the
bright copper that I sanded the patina off continues to darken and
loose its bright warm copper color. Has anyone else had trouble with
this? Does anyone else have any idea as to how to go about preserving
the color? I’ve talked to Jax a couple of times, and they assure me I
am doing everything correctly. They promise me that rinsing the
copper in water with stop the chemical reaction. I don’t want to use
liver of sulfur because I love the warm tones I get with the Jax. Can
anyone help?!?!?

Denise


#2

Well, I can’t help, but I too am looking for a way to keep the
copper bright under Renaissance Wax. So far everything has slowly
darkened to a rich orange brown. Very pretty, but not what I want.

Kelley


#3

I love to put patina on copper also, but I do it by using a torch,
then Handy Flux, more torch, and then crossing my fingers and
holding my mouth right. I usually don’t try to keep any bright spots,
but, to preserve the color try using a spray meant for cars. I think
I got mine at Auto Zone. I was told this at the Italian jewelry
school Alchimia. I am not sure if it comes in a matte spray or not,
it does put a bit of a sheen on your piece. Mostly though, I want to
let the copper do its own thing. Don’t cheat and use the first clear
sealer you find, hunt for a intensive spray meant for cars.

Good luck, Roxy Lentz


#4

I had the ‘pleasure’ of seeing some of my patinated work in copper
with knocked back highlights dull where the bright portions were
shall I say not so bright!!! I’m really of the thought that it is
the Rem wax and not your patination technique/product. Anyone else
weigh in here please because I used to cherish Ren wax on my wood
objects…but not so much on copper.

John Wirth


#5

Hello Denise,

If the copper were completely polished, everything would be fine,
but the problem is that the copper has been patina’d, which means
that it is contaminated. Renaissance Wax doesn’t protect surfaces that
are already contaminated. Basically by sealing the copper with
renaissance wax you have encapsulated the contaminant around the
copper.

The only way to retain both a patina and shine next to each other is
by sealing the piece in lacquer.

There are dip-able lacquers available from most suppliers, but this
stuff usually runs and looks off, it can make a beautiful piece of
jewelry look terrible. I have seen people use spray can lacquer but
they apply several very thin coats which can take forever because the
spray can stuff usually takes a long time to dry. If you want a smooth
surface, you will need to get an airbrush which will allow you to
apply a perfect coating with the least hassle.

As far as the lacquer to use in the airbrush, you can use the same
dip-able lacquer but you will have to thin it so it doesn’t spatter
onto the piece.

I hope I was helpful

Take care
Kenneth, DynastyLab
benchofanapprentice.blogspot.com


#6

Hello Kelley, et al,

When I want to preserve a bright copper finish, I spray with Nikolas
brand Clear Lacquer, #2105. It is designed to protect tarnishable
solid or plated metals. Apply at least two light coats - more is
better. HOWEVER, like any lacquer, if there is any flex in the metal,
the finish will pop off and the metal underneath will patina.
Although durable, the finish will gradually wear off on the high
spots when worn.

For the most part, I embrace the patina on copper and incorporate
the “tarnished” metal in my work. When polished copper is used, I
inform my clients to expect a patina to develop. I wear a hammered
copper cuff to show an example.

Judy in Kansas, where (would you believe it!!) temps are to be back
in the 90s today!


#7

I will “ditto” Roxy. In the auto industry this product is called
"Clear- Coat."

Gary Strickland, GJG


#8
The only way to retain both a patina and shine next to each other
is by sealing the piece in lacquer. 

Unfortunately lacquer is no more a solution than the wax. All
coatings will allow continued patination if there is any
contamination on the surface.

James Binnion
James Binnion Metal Arts


#9

Has anyone tried the UV coatings use on circuit boards? I use it on
fishing lures and it is great… 10 seconds under the light and it is
a very tough coating that protects my undercoatings and paint. Might
be worth investigating.

Vernon Wilson


#10

I’m beginning to wonder if Ren wax is intended for other art work and
isn’t ‘thick’ enough to give protection against oxidation. For my
copper work it seems that good wooden floor wax is working better. An
earlier post mentioned auto clear coat spray…that’s an idea that
I’ve been kicking around for a while. Sheen will be an issue though.

John


#11

Is there a particular name for this car spray? Is there one brand
that’s better than another?

Francesca Anatra


#12

It’s my understanding that copper darkens because of oxygen. So, if
we can get a good seal it shouldn’t darken. I’ve tried several
different sealants with varying results. So far, the best has been a
spray lacquer which is used to seal charcoal drawings. Art supply
stores carry it. I was not happy with an automotive lacquer. I have
had a strange phenomenon however, and I wonder if we can learn
something from it. Sometimes my copper begins to darken immediately,
but if I bring it to a high shine, it takes much longer for any
darkening to start. I can’t figure out why. Does the polishing cause
the surface to become less permeable by oxygen? What would it take to
make it impermeable? Having said that, one of the things I really
enjoy about copper is the way it ages/oxydizes. It develops beauty
as it ages. Also, If you mix a little salt with some lemon juice and
wash your copper in it, it will brighten easily.

Dick


#13

Okay this is how I look at copper oxidation, for me I have fair skin
and freckles, others have darken skin and tan. Now we get the "tan"
to help protectour skin from further sun damage, the oxidation on
copper is like the “tan”. It will only turn a color from the natural
salm on color if introduced to any kind of atmosphere. Depending on
the makeup of the atmosphere the copper will oxidize to a level to
protect the copper the “tan”. Freshly polished has the “tan” removed
and since it is clean it will not tarnish as quickly, it has no need
to “tan” because it does not need to protect itself yet. But once it
gets anything on it then it will try to protect its self. Depending
on the chemicals on the copper it sets a different protection level,
which are the different colors that it can turn and we call it
oxidation, our patina palette.

Warren Townsend
www.metalrecipes.com


#14
Does the polishing cause the surface to become less permeable by
oxygen? 

One factor may be that polishing actually reduces the surface area
exposed to air. A rough surface can have much more area:

^^^^^^^^^^^^^

versus

Al Balmer
Pine City, NY


#15
It's my understanding that copper darkens because of oxygen. 

Yes, but also because of other copper salts or compounds formed by
reacting with things other than oxygen. Sulphur is the main one I’m
thinking of. Just as sterling silver tarnishes from forming black
silver and copper sulphides (not, by the way, oxides, at least not
for the black tarnished colors), so do copper and it’s alloys. You
can verify this by darkening your copper with a liver of sulphur
solution, just as with sterling silver. What is formed is sulphides,
not oxides. Copper oxides come in two versions. Only one of them is
actually black, the other is red. That’s why heat colored copper can
show those lovely reddish tones in addition to just blackening.

However, in terms of your question regarding sealing, the issues are
similar.

So, if we can get a good seal it shouldn't darken. I've tried
several different sealants with varying results. 

Some so-called sealing agents are sufficiently gas permiable as to
slowly allow oxygen to penetrate (even gold electroplate will allow
this if it’s thin). And since oxygen isn’t the only issue, it also
matters whether the sealing agent itself has some sort of sulphur
compounds in it, as these can directly react with the copper.

.... Sometimes my copper begins to darken immediately, but if I
bring it to a high shine, it takes much longer for any darkening to
start. I can't figure out why. Does the polishing cause the surface
to become less permeable by oxygen? 

The reactions with either oxygen or sulphur or other chemicals that
will cause patinas to form happen on the surface. Not under or within
it. The metal does not need to be permiable to oxygen, gasses, or
chemicals in order to tarnish. What is happening, however, has to do
simply with surface area. The smooth polished surface has less
surface area than a rougher unpolished surface, so less area
available to react. Even if the same percentage of a surface forms
oxides or sulpides, the surface area of the polished surface is so
much less that visually, the amount of visible tarnish shown by that
same percentage, will be much lighter. Also, the rough unpolished
surface will have pits and pores and a texture at the microscopic
level that can trap reactants more than a smooth surface will, so it
can be more reactive. As well, in polishing, the wax or grease based
polishing compounds will tend to fill microscopic surface pores,
acting a bit like a sealant already, unless you use fairly
aggressive cleaning methods (like an ultrasonic) that will remove
that invisible stuff from any surface pores.

make it impermeable? 

Inpermiable coatings, electroplatings, modifications to the alloy,
or the like. If a given metal or material is gas permiable, changing
the level of polish won’t affect this.

Peter


#16
Unfortunately lacquer is no more a solution than the wax. All
coatings will allow continued patination if there is any
contamination on the surface. 

Accept reality. Copper ages and the colours will change period
regardless of what you do.

Stable colours… work in titanium (delightfully light but harder to
work than copper) or use niobium which colours better and is easier
to work. Neither metal can be soldered in air. Maybe under an inert
gas or high vac chamber or a space trip. All rather difficult in a
small shop :slight_smile: No glue but rivets or other mechanical techniques are
fine. Both are nice metals just different.

jeffD
Demand Designs
Analog/Digital Modelling & Goldsmithing
http://www.gmavt.net/~jdemand


#17
Is there a particular name for this car spray? Is there one brand
that's better than another? 

Rats! I knew you would ask me that! I took it with me to my last
show to put on a piece, and in the rush to pack up, misplaced it for
now. I am pretty sure it is called “perfect Match”. I bought it at
O’Reilleys (spelling) and they had two kinds. I don’t remember
anymore why I thought one would be better than the other, but I
waited until they got the more expensive kind in. So far I am pretty
happy with it. I don’t use it often, but I put some on some copper
earrings I had put green patina on by leaving it in sawdust mixed
with ammonia, salt and vinegar, and it has done a good job of
preserving the patina, and keeping it from rubbing off, without
being a distraction. One thing is for sure, you have to use this
stuff outside. Don’t even think about using it indoors. At Alchimia
they stressed to use the kind meant for cars. I suppose it is
formulated to withstand elements better.

Roxy Lentz


#18

Thanks for the I have an O’Reilly’s just down the
street.

Francesca


#19

Francesca,

I wish I could give you more specific info, but I think one can was
small, and one was larger, and the small can is the one I used, it
was also a bit more expensive, but not so expensive you feel as if
you wasted your money if you didn’t like.

Roxy