I’ve always enjoyed playing at alchemy - chemistry without actually
having a clue what I’m doing. So I’m not sure that what I discovered
today is actually safe. I was messing around with potential
patinating agents, and just happened to try ordinary chlorine bleach
(sodium hypochlorite). I found that it turned sterling silver matte
black in approximately two to five minutes, depending on hardness.
That makes it a cheap, fast and readily available patinating agent.
But like I said, I am not a chemist. Have I stumbled onto a neat
shortcut for oxidizing silver, or developed a WMD?
I’ve always enjoyed playing at alchemy - chemistry without actually
... I was messing around with potential patinating agents, and just happened to try ordinary chlorine bleach ... Have I stumbled onto a neat shortcut for oxidizing silver, or developed a WMD?
I’m certainly no chemist either but I’ve tried this and I like it!
I’d read about using bleach but the references always said that the
result was “light grey” and that didn’t sound particularly appealing
to me so I did not pursue it.
After your post I did some basic tests and experiments and thought
the others in the group might be interested. The bleach patina:
is dark grey with some brown mottling on clean, de-scaled sterling.
is deep dark grey on clean, depletion guilded sterling, much denser
and more even that bare sterling.
turns very dark grey or black under light oil or waxing.
stands up to moderate abrasion reasonably well, becoming a glossy
black where the patina has resisted being removed.
polishes to a warm semi-gloss deep black with red rouge.
is quite resistant to citrus fruit juices, tomato juices and
vinegar. Acetone will lighten the patina somewhat, enhancing the
browns in it.
is quite resistant to everyday heats and heating. When heated to
200C or more the patina does bubble and degrade but rather slower
than one might expect.
is remarkably resistant to the pickling process (I use citric acid
is much improved if the bleach is warmed. An 8 hour soak at room
temperature yields a patina that is inferior to that achieved after 1
minute in bleach that has been warmed to 80C (chemical gloves, vapor
mask and good ventilation recommended). The latter patina is much
more even and has a deeper, richer look.
So, there it is. I’m sold … unless of course we hear that we’re
putting ourselves at risk somehow with this.
Given the issues identified with increased brittleness in gold
alloys exposed to chlorine bleach in swimming pools and hot tubs, is
this exposure in sterling possibly going to create similar issues? I
don’t frankly recall whether the issue was deterioration or chemical
changes in the copper or in another allying metal and can’t find the
study in question – just remember some rather dramatic photos.
Hand-crafted artisan jewelry
This is a weird one silver would form the chloride which is white…
I tried the Kaboom treatment too and saw some chloride white but
never got a black color at all.
I haven’t tried this one but ???.
Black would might indicate a mass of white particles or extremely
fine rough that adsorb all incident light instead of giving the
white high reflectance appearance normal with silver.
The info Trevor presented gets right into the stuff of chlorine used
as a patina chemical. My concern is the possible effect chlorine
might have on solders, copper in the alloy, etc.
I do know that nickel bearing white gold is totally unforgiven by
chlorine and severe damage to the alloy can occur from exposure.
Does anyone know if chlorine might affect silver alloys? Most say
that without nickel content all is just fine but experience makes me
question this at least in part. I have seen low karat yellow gold
items “apparently” damaged by chlorine exposure. If copper has
anything to do with the effect, silver could be damaged. I simply do
not know the answer to that.
Have you tried the “chlorine patina” in an ultrasonic? Some patinas
come right off.
In my own experience, chlorine is not to be played with and is not
taken seriously as this chemical should. Heating makes me wonder
about free chlorine gas in the air. If you have ever breathed the
gas itself it is not a kind experience. As for me, I will still go
for the old basic liver of sulphur.
Peace to all.
A related question that just came up for me: does the manufacture of
sterling silver differ enough to make different batches "take"
patina better than others? Less copper? I have bottle of true-black
and it did a few pieces great, then it just fogged it and greyed it,
then it did black again. Not a clinical test though - could have been
anything, I guess (my finishing, cleaning, etc). But it was different
source of silver.
In reading this thread, I thought about another thread quite a while
back that talked about brittleness occurring in gold when worn by
frequent swimmers (brittleness related to the reaction with chlorine
in the swimming pool or hot tub).
Is either streling or fine silver subject to the same brittleness
One thing I haven’t seen on this thread about patina on silver is the
need to heat either the solution or the silver. I have tried it many
times both ways and found that it is easier and more effective to
simply lay the silver on a hot plate (same one we heat our pickle on)
for 20 or 30 secs and then paint on the solution (we use JAX). The
results are astonishing. The patina is instant and very black. It is
also quite durable. Try it.
Cheers from Don at The Charles Belle Studio in SOFL where simple
elegance IS fine jewelry! @coralnut2
A related question that just came up for me: does the manufacture of sterling silver differ enough to make different batches "take" patina better than others? Less copper? I have bottle of true-black and it did a few pieces great, then it just fogged it and greyed it, then it did black again. Not a clinical test though - could have been anything, I guess (my finishing, cleaning, etc). But it was different source of silver.
Roseann, More likely that variances in your silver (unless one
batch was actually fine silver instead of sterling), might be
variances in what you did with it. If you’ve soldered and piece
without a fire scale prevenative like prips flux, and then pickled
it, perhaps several times, which gives you that matte white surface,
you’ve depleted surface copper, leaving a fine silver surface on the
sterling. How it then takes a patina will depend on whether your
subsequent finishing and polishing operations cut through the fine
silver layer again to the sterling alloy. That could easily vary from
piece to piece.
Have you tried the "chlorine patina" in an ultrasonic? Some patinas come right off.
I don’t have an ultrasonic so I couldn’t say. I’d be surprised if it
did though. That patina is stuck on there pretty darn good. It does
bubble up if you heat it a lot, as in several hundred degrees C, so
maybe the ultrasonic would zap it off. I just don’t know.
As for me, I will still go for the old basic liver of sulphur.
Absolutely, but let’s not forget the subject here. "Quick and dirty"
it is and given the option I’d use more traditional methods too.
Unfortunately I don’t have that option at the moment (long story) so
for me this is a useful discovery and it was in that spirit that I
offered the results of my tests and experiments.
I fully appreciate the safety concerns --you’ll note that I did say
to use chemical gloves and a vapor mask and work in a well ventilated
area-- but let’s be realistic. Compared to some of the acids and
other chemical cocktails that are often to be found in the jeweller’s
studio I don’t think regular household bleach is going to rate too
high on the “Most Wanted” list. Appropriate caution and care of
course but given that I don’t think a little “can do” spirit is going
to lead one too far astray here.
I suppose a worthy footnote here is that I’ve only tried this on
sterling and fine silver. I understand that it would have little or
no blackening effect on most gold alloys and frankly I have no
intention of trying.
In reading this thread, I thought about another thread quite a while back that talked about brittleness occurring in gold when worn by frequent swimmers (brittleness related to the reaction with chlorine in the swimming pool or hot tub). Is either streling or fine silver subject to the same brittleness issue?
No. Neither, generally, are most yellow golds, or platinum. Some
lower melting solders, including very easy silver solders, might be
slightly affected, and silver or silver solders can have their
surfaces discolored or tarnished by chlorinated water. But the
cracking and brittleness seen in white golds does not, so far as I
know, occur with silver.
Orchid is so much fun!. Chlorine patinas for silver? Take
precautions: follow along here…
Chlorine (chemical symbol Cl) is a member of the halogen family
(located in Group VIIA of the periodic table) and are a particular
class of “nonmetals”. The halogens are particularly reactive
(especially with the alkali metals). The alkali metals are the
elements located in Group IA of the periodic table. These nonmetals
are located on the upper right side of the periodic table. Nonmetals
are separated from metals (like Cu, Au & Ag - copper/gold/silver) by
a line that cuts diagonally through that region of the periodic
Important Chemical properties of Chlorine:
Chlorine is “corrosive” to some forms of plastics, rubber, and
coatings. It is soluble in chlorides, alkali, and alcohol’s.
Chlorine (in it’s gas state) reacts explosively or forms explosive
compounds with many common substances such as acetylene, ether,
turpentine, ammonia, fuel gas, hydrogen, and finely divided metals.
It is a noncombustible gas, and a strong “oxidizer”. Remember the
thread about rusting files?
Chlorine (in it’s gas state) is heavier than air, and less
water-soluble than ammonia. Water dissolves about twice its volume
of chlorine gas, forming a mixture of hydrochloric and hypochlorous
acids. It can be an eye irritant, respiratory irritant.
Here is the danger: Chlorine (Cl) reacts with ammonia or acids to
form toxic gas. Danger: Most chlorine bleaches are labeled as a
"corrosive". Household bleach (used to whiten fabrics or remove mold
from surfaces) is a 5% solution of a stabilized form of chlorine.
Do Not Mix household bleach with acid-containing or
ammonia-containing (cleaner) substances. Dangerous levels of a very
harmful gas can be created by these mixtures.
Remember those pH levels discussed in another thread previously?
Thinking this through; we do not want to unintentionally make our
studios into little laboratory experiments. Vinegar (pH of about 3.0
- acidic) differs from ammonia (pH of about 12); the smaller the pH
number the more acidic - conversely, the higher the pH number the
The thing to remember about Chlorine (and several other gases) is
that in the presence of water (moisture in the air) they form acids.
In the case of Chlorine the acid is Hydrochloric acid (and/or
Hydrochlorous acid) and this will react with metals to form their
Chlorides. Copper Chloride is green, silver chloride is white but
goes grey on exposure to light. A number of anti-scale compounds and
drain cleaners contain Hydrochloric acid and so it is always prudent
to remove jewellery when using these products. Another chemical to be
very wary of is Ammonia (as in Bleach), this can work its way into
the grain of metals and then, as it absorbs moisture from the air and
expands in the confined space, it can literally blow the grains of
metal apart. This is a particular problem in my field of watch and
clock repairing where the cleaning solutions used for many years
contained ammonia. A particular problem known as ‘brass
embrittlement’ in which the cast and then hammered brass wheels of
clocks were literally turning to powder, taxed the brains of the
scientists for years until it was realised that it was the ammonia
staying in the microscopic cracks between the grains of metal and
forcing them apart in a quite spectacular way.
Ian W. Wright
One thing I haven't seen on this thread about patina on silver is the need to heat either the solution or the silver.
It was mentioned in
"- is much improved if the bleach is warmed. An 8 hour soak at room temperature yields a patina that is inferior to that achieved after 1 minute in bleach that has been warmed to 80C (chemical gloves, vapor mask and good ventilation recommended). The latter patina is much more even and has a deeper, richer look."
I’ve since tried it with the bleach at other temps and find that
50-60C seems quite sufficient to produce a deep patina in a matter of
a minute or two. Longer makes it slightly darker and “deeper” but I
suspect that once the surface silver has been transformed the actual
reaction taking place tapers off pretty rapidly and therefor there’s
little change beyond that point.
I’ve tried heating the work pieces too but my pieces are quite small
at this point, only a couple grams worth, and am finding they come
out better if the solution and not the pieces are warmed. I making a
50 gram sterling bracelet next so I’ll try your approach with it.
Maybe the larger mass will carry enough heat in it to achieve
basically the same effect.
Did a little bit of rooting around for more info on this subject. I
discovered that there’s been some amount of discussion of it at
rec.crafts.jewelry over the years including the following from our
own Mr. Rowe:
"It should also perhaps be mentioned that bleach as a silver oxidizer is somewhat less than completely consistent and reliable. Leave it too long and it will end up dirty grey and blotchy, not dark, and it never really gives you the best black appearance. And, the surface it gives you is not as dark as that obtainable by more traditional silver oxidizers. If you simply wish a used/antique/worn look, it may be superior. But if you want a nice clear good looking black or dark grey, it's probably the wrong choice. ... Some artists might like the results, or hobbyists might appreciate not having to go buy something else for only sporadic needs, but it's not considered a normal, traditional, or professional solution to oxidizing silver."
As usual liver of sulphur is oft mentioned as the preferred
In any case we’re certainly not the first ones to be messing with
bleach as a patination agent on silver. As ever our fellows have gone
CalEnamelist is right: And – again, from the chemist’s viewpoint
– silver plus chlorine in an acid solution is going to produce –
silver chloride. This is what your “patina” is. (The same thing as
the image on your vacation photos.)