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Organic oxidyzer for copper?


Hi, Im working on a batch of hammered and repousseed (sp?) copper jewelry that Id like to oxydize for more visual depth. I live in
some of the most untouched country in the “civilized” world, which is
maintained by a focussed effort from everybody that lives in this
area, to not use anything that might upset the balance. So Im looking for a non-harmful, easily available and safely disposable alternative to hydrochloric acid in order to oxydize these copper pieces. I know about salt and Vinegar, but Im shooting for black
oxydation, rather than green crusty (toxic!!) verdigris.

(I LOVE the fact, that one can use lemon juice as pickle…thanks
to you guys sharing your knowledge, I can feel much better about
soldering now :-)))

Thanks for your time,


Liver of sulphur is non-harmful and disposable, it’s just stinky.
There have been previous threads (see the archives) about liver of
sulphur (under a different name) being available from plant

Lee Einer


Why not use lime sulphur?? It does the same thing as liver of
sulphur and can be used the same way – and will end up with a black
coloration – and as it is sold commercially as a garden fungicide.
There was a thread on this on Orchid about 3 months ago. Check the
archives – someone there had a place on the web where it could be
ordered if it is not available in your area.

Laura Wiesler
StoneHouse Studio


Hello Sparrow

Here in Calgary I get a liquid called ‘Silver-Black’ made by
Griffith, which are carried by many suppliers in the US. It is good
for a “smooth black patina on silver, gold, copper and bronze.” I
have used it with great success on silver, copper, brass and bronze.
It does have hydrochloric acid as an ingredient but to apply you just
brush on with a cheap paintbrush, let it dry or wipe off excess with
a tissue and you are done. It does work a little faster if the piece
is warm; I will on a larger item (e.g. bracelet) set it on a hot
plate until warm. Smaller pieces I don’t bother to warm. You don’t
have to rinse off and dispose of anything. Usually it runs about $6-8
for a 4 oz bottle and mine is at least 2 years old. It is already a
yellow liquid and as long as you replace the lid tightly will last
for years. It is still good to have good ventilation though.

Karen Bahr “the Rocklady” (@Rocklady)
K.I.S. Creations
May your gems always sparkle.



Hydrochloric acid is a naturally occurring material - we make it in
our stomachs all the time. Using it sensibly is safe for the
environment. You neutralize it with sodium hydroxide and this
combines with it to form water and common table salt.

Tony Konrath
Key West Florida 33040


G’day; Now I’ve come all over academic (Shame, shame!!) The
word ORGANIC has had it’s original meaning considerably changed in
the last half century. If applied to a material it used to mean
that the material was the product of some life process, and the
word INORGANIC was applied to anything that was not the result of a
life process. Thus all vegetables, plants and animals are organic
in origin. Thus to talk about , say, ‘organic lettuces’ is
nonsense - or course they are organic. Inorganic lettuces don’t
exist. So if you take a lettuce seed and grow it in a fertilizer
made of minerals (nitrates, sulphates, iron, cobalt, selenium etc)
that lettuce is still organic. So it was grown with inorganic
fertilizers instead of life produced ones (like manure, compost,
etc), but it is still organic.

Lets consider a material used by jewellers; ‘Liver of Sulphur’
(potassium poly sulphide) is inorganic; made from potassium and
sulphur. ‘Lime sulphur’ (calcium poly sulphide is made by heating
lime with sulphur. So it is an inorganic blackening agent for silver
and copper.

You want an organic agent? Well, stew your silver or copper with
onions, or garlic, and the organically produced sulphur compounds in
these once-living plants will blacken the metals. And by the way,
whilst I’m being academic, the silver or copper is not oxidized to
blacken it; the metals are sulphided!!

OK, so what about limestone, calcium carbonate? Bit confusing here.
Most limestone is the product of marine animals which once lived,
BUT - and here’s the confusion. Before life formed on this earth,
there was calcium carbonate, and some of it still exists. Well,
organic or inorganic? So you see things get difficult if one tries
to be too clever! These days chemists try not to mention the two

Cheers for now,
John Burgess; @John_Burgess2 of Mapua, Nelson NZ


Thanks everybody for your detailed answers. I definitely have some
things to experiment with now. I really appreciate this list for all
the I get from the people here, and I wish I had more
time to contribute, but alas, between Kid, Horse, House, Garden,
Dogs, Music Practice and Jewelry making…etc. time is short.



Well, I lightheartedly mentioned egg yolk here a while back, for
just this job. Egg does blacken silver, and it’s about as organic
as it gets (buy “organic” eggs, of course…). That said, and
admiring the sentiment and motives behind the original question (and
it sounds like a great community), unless you’re using industrial
quantities wouldn’t it be admissible to use one of the more usual

Or, just had a thought … cabbage water! Maybe, just maybe,
boiling silver with some cabbage or other brassica might blacken it.
Brassicas contain sulphur compounds. So do onions. Hey, so does

Kevin (NW England, UK)


I’m going to nit-pick… “Organic” refers to carbon compounds - not
once living material. & Oxidation is the loss of electrons, reduction
is the gain of electrons in a chemical process.

OK Nit-picking over!

Tony Konrath
Key West Florida 33040


Hi Kevin, What you say remind me of two little things. An old man I
used to know used to go into the woods looking for mushrooms. The
problem was that some mushrooms were dangerous. As a test, he used to
warp the mushrooms in a towel together with a (rather large) silver
coin. If the silver blackened, there was a problem with the
mushrooms. I never figured out whether this test was valid or not (I
don’t think it’s valid, but the fact is that silver sometimes got
black and sometimes not). Another man I used to know from our village
was a metalsmith. He worked with silver a lot. If the silver was
dirty, for example, through contamination, he used to put jam on it
(I guess sugar water would work too) - this is really true. He would
then heat the piece with his torch and when really hot, throw it in a
pickle solution. The silver was instantly clean. Amazing person. I
have no explanation for this, but I saw with my own eyes that it
works. I had contamination a while ago - my silver looked rosy and
even ammonia didn’t help. I used my tumbler on it.
But next try I’ll try jam. Best, Will


Some people in India were reporting a problem with high karat gold
(22k) tarnishing. It turned out that a diet high in onions and
garlic (curry anyone?) was the culprit. So you can do patinas while
you prepare dinner!

Spike Cornelius
Portland, Or.
RC ArtMetal

   I'm going to nit-pick..... "Organic" refers to carbon compounds
- not once living material. & Oxidation is the loss of electrons,
reduction is the gain of electrons  in a chemical process. 

G’day. No arguement. BUT if you want to be really academic it
refers to compounds which have TWO or more carbon atoms. In that
case no carbonate is organic. Only things like Ascetic acid
CH3COOH and so on. I was trying hard not to confuse people who don’t
want academic, nit picking answers, so there, nyaaah!!

Cheers for now,
John Burgess; @John_Burgess2 of Mapua, Nelson NZ


Hi John, What about methane or methanol? ;^) David


Thanks again for everybody`s answers…:slight_smile:

That said, and admiring the sentiment and motives behind the
original question (and it sounds like a great community), unless
you're using industrial quantities wouldn't it be admissible to use
one of the more usual recipes? 

It is a great community! about as rural as you can get without
living in a desert, the river is one of the last rivers that is in
it`s natural condition. The water is some of the cleanest on earth
(less than 1% of the planet’s water supply is this clean. Most of the
people that live here are artists and crafters of some sort.
Alternative lifestyles are encouraged. Our local tourist trap
(besides the caves) is a treehouse resort,…go figure :slight_smile:

and yes, it would probably be ok, to use chemicals on an occasional
basis. But I personally would like to do as much as I can to leave
only footprints and do as little damage and as much healing as
possible to this planet, our home.

off for the weekend show :slight_smile:


It needs a carbon- hydrogen bond i.e. to be a hydrocarbon. This
makes an “organic” chemical. Jesse


Hi William, You say: " If the silver was dirty, for example, through
contamination, he used to put jam on it (I guess sugar water would
work too) - this is really true."

Acid (e.g.,citrus) may have been crucial. Thus, type of jam may be

Janet in Jerusalem


Hello Janet, I was still young, but it really happened. He put jam
on the thing and started to heat till till the piece smoked and was
all black from the burned carbon. Then he threw it in a pickle, took
it out, cleaned it a bit, and the piece was clean. I have been
thinking about this the last couple of days and considered the
possibility that he played a trick on me - maybe he just did
something crazy in order to make a kid laugh. I don’t think that his
pickle solution was Sparex … However, yesterday we had a party
going on here and since everyone was chatting for hours about
fascinating stuff such as the colors of the curtains for a new house
on which we haven’t decided yet, I escaped to my room, took a piece
of sterling silver sheet and a selflocking tweezer from steel and
contaminated the thing in old pickle. After that I put strawberry jam

  • the first thing I could find - on it and to heated the piece till
    it smoked and was black. I then ‘quenched’ it in a new (and I have to
    say strong) pickle solution (the usual Sparex but more than usual):
    go over it with a cloth and the silver is clean. Just try it out for
    yourself. It gave me a good feeling. I don’t know what my family in
    law thinks about it. I am not a chemist, but I suspect that it
    doesn’t have to do with citric acid or anything like that. It is as
    if the layer of contamination somehow reacts with the carbon, which
    seems to suck it up or something. I might be totally
    wrong on this. Best, Will

It is as if the layer of  contamination somehow reacts with the
carbon, which seems to suck it up or something. 

Or it could be simpler. Try this one. contaminate your silver to
copper plate it the same way, then, without flux or other covering,
anneal it. Now pickle it in the same strong pickle. I’ll bet your
copper will also be gone this way.

Heating the silver enough to carbonize the jam will also allow the
copper to oxidize, and the copper oxide layer thus formed would
quickly pickle off. the carbon you put down is porous enough that it
will easily let atmosphere through, and i doubt you were hot enough
for the carbon to be actively scavenging the oxygen from the copper.

Also, as you heat, the very thin layer of copper will at least
partially start to dissipate into the silver, again giving the
appearance of cleaning it off after pickling.

And, since you say you’re using really strong fresh pickle, allow me
to point out that metallic copper, not just copper oxide, is attacked
by sulphuric acid, and since your pickle is a sulphuric acid salt,
your pickle will also slowly attack the copper. So try this one
too. Again contaminate a piece of silver with copper. This time,
without additional heating or anything, pickle it in new, strong,
sparex solution. See how long it takes for the copper to just be
dissolved off by the pickle itself without any other mechanism.

I’d guess the only thing the jam might do is provide at least a
little bit of protection against fire scale, since the amount of
oxygen getting to the silver surface will be reduced, and of course
the copper on the surface will tend to react with that before the
oxygen gets down into the copper alloyed with the silver. Whether
it’s a measurable degree of protection or not, might be an
interesting experiment, since if so, there are other easier ways to
apply a carbon coating. Any acetylene flame, without enough
air/oxygen to burn cleanly, will leave soot (carbon) on any surface
it’s applied to. So if you find a carbon layer appreciably reduces
fire scale or fire stain, or some such, then if you’re working with,
say, a prestolite type (air/acetyelene) torch, then it might be
possible to just soot up the piece by covering the air intakes on
the torch tip, before heating. On the other hand, perhaps the jam
IS needed for this, since it would also supply organic binders that
might help bind the forming carbon to the surface, or in burning the
jam to form the carbon, perhaps additional beneficial activity
occurs, much as it seems to when we use an organic glue binder in
granulation. It might increase the protection afforded by the carbon
alone, or it might just help hold the carbon in place. Who knows.

Might be worth playing around with, however.

Have fun.


Is it possible that the burning sugar in the jam consumes all
available oxygen and thus removes surface oxidization? I believe Lee
Epperson uses a similar technique (but with dry leaves or sawdust,
not preserves) to clean up his sterling silver castings.

Lee Einer


G’day; before we start, let me suggest that if you are bored
stiff with this subject, just click ‘delete’. If you really HATE
it press ‘shift delete’ and it won’t even go to ‘Trash.’

To clear up my own thinking at least, let me explore the ideas
concerning "what is the meaning of the terms ‘organic’; and
’inorganic.’ "?

My first concern with chemical nomenclature came when I left school
at 14. I became a lab boy in 1935 in a Technical College Chemistry
Department. The Department had four separate stores for chemicals:
inorganic, organic, pharmacy, and so called inflammables but I
suggest pharmacy and flammables doesn’t really enter this argument.
So, someone would come to the stores and ask for say, nickel
chloride, so we went to the inorganic store. Someone else wanted
phenol which was organic;. fine. But it took me a while to discover
where sodium acetate should be kept; but it was considered
inorganic. One learnt by experience but it didn’t seem logical to
me. Then the next place I worked there was only one main store
with chemicals in alphabetical order; much more intelligent; with
separate stores for flammables and bulk acids. The problem then was
purely a matter of spelling. Sodium hydroxide or caustic soda?
Phenol, carbolic acid or fenol? So when I became the first
laboratory steward for a University chemistry department in a brand
new building, storage systems were up to me; I had to arrange for
the quick, easy transfer of thousands of bottles of chemicals.
(by labour which knew no chemistry) Simple. All bulk acids and
solvents in The Safety Store. All chemicals in alphabetical and sub
alphabetical order. What if a chemical had multiple names?
Natrium sulphosaures;? sodium sulphate? Or; Potassium
thiosulphate? Hypo? Hyposulphate? etc. Simple. Put them on the
shelf under the principle name given in either The British Drug
Houses catalogue, or L Light and Sons catalogue. and re-lable if
necessary. (Any unlabelled bottle or package must be instantly
disposed of; no ‘guided’ guessing allowed. Disposal mandatory.).

So now we tackle the crux of the problem. So far as chemistry is
concerned, the division of “if it is the product of life it is
organic. Otherwise it must be inorganic” That definition went out
of use. long ago.

So it became , “if it has a carbon atom, then it must be organic;
everything else is inorganic.” So is really ancient (4 billion
year old) calcium carbonate organic? Yes it is. it has one carbon
atom Or is it? Life wasn’t ‘invented’ at that time.

But there came a compromise “Chemicals with two or more carbon atoms
are organic; all else is inorganic” Thus calcium carbonate is
inorganic; Ca2CO3 . So is methane CH4. Acetic acid is organic.

And that is how it stands at the moment. But there doesn’t seem
much point in the argument any longer.

HOWEVER!!! We now come to the present day ideas of what does
the word ‘Organic’ means as applied to food. Using the old
laboratory criteria; all food is organic; we cannot thrive on
anything which has not lived or is not the product of life. The
word 'Organic" in modern speech has come to mean ‘chemical or
not-chemical.’ Man made. Thus a food crop fertilized with manure or
compost has been termed organic. A food crop fertilized with
ammonium nitrate, ‘superphosphate’, etc is not “organic” in those
terms. (It isn’t inorganic either!)

BUT: a crop grown without pesticides is also called 'organic’
So what about apples grown with the use of manure or compost, but
sprayed with a chemical to guard against spoilage by codling month?

At this point I abdicate, saying “Life gets tejus don’ it?” And ,
“Fings ain’t wot they useter be”

And I plead guilty of the crime of academicity on the grounds of

Cheers for now,
John Burgess; @John_Burgess2 of Mapua, Nelson NZ