Way back in the early 70’s, I took a class in electroforming with
Stanley Lechtzin at Tyler School of Art. I forgot most of what I
learned there, but I remember one thing vividly: the concept of metal
being “chemically clean”. When the metal is chemically clean, if you
dip it in water and pull it out, the water spreads out in a thin
layer all over the surface of the metal instead of beading and
rolling off. The process used in the class to achieve this state
involved electroplating equipment. I don’t have electroplating
equipment, and I don’t know if there are other ways to get metal
chemically clean, but I know that pickling doesn’t seem to do it. Do
any of you out there have any knowledge about this you could share?
It may not be science but it is effective and inexpensive. Get one
of the square batteries (I’m guessing 4x4 and maybe 6 ins high) and 2
pieces of wire hooked to the leads with alligator clips to use as
the source of electricity and follow the directions for plating and
electrocleaning. It may not look fancy, has no dials or bells and
whistles, but it works.
When I demonstrate “No Name Patina Prep” the sheeting is what we look
for. It takes only a moment with hot water and a slurry of the
product to make the rinse water sheet on the surface. Clean and ready
for a great even patinas and transparent enamels for that matter…
The old fashioned way… soap, pumice and water.
We clean (gently scrub) with Bon Ami cleansing powder - not a Clorox
based brand, (or Pumice), and a soft toothbrush until we achieve the
"sheet off" of water - as in jelly making - (eliminates the spotty
appearance). Rinse thoroughly and hold by the edges of the metal. No
harsh chemicals, very effective. Bon Ami’s trade mark is that “it
hasn’t scratched yet!” If you are careful there won’t be scratches
in the metal.
We sell a product just for this purpose it is called Midas Metal
Kleen stock # 335-118. Also a 1 to 100 part mixture of nitric acid to
distilled water works well too.
Hope this helps.
Sincerely,
Thackeray Taylor
Rio Grande Technical Support
505-839-3000 ex13903
800-545-6566
You do not need complicated equipment to electro clean jewelry. Just
a source of power, anything from a 9 volt battery to a battery
charger or small transformer (like the wall plug in transformers used
to power all our electronics) and if it is AC a rectifier (diode) to
convert it to DC.
David H. Cleinman said in American Jewelry Manufacturer, June 1984:
"Electrocleaning: When an electrical charge is passed through a
soak cleaner, the process is called electrocleaning. The
electrocleaning solution is basically the same as that used in
soak cleaning; it operates at the same temperature ranges of
140 F to 180 F with a pH of 10.5 to 11. The introduction of a
direct current creates a bath in which the hydrogen molecules
form at the cathode and create a "scrubbing" action on the
work part. This method of electrocleaning is called direct
current cleaning.
When used with a mild alkaline solution this type of cleaning
will not etch or tarnish the surface of the metal. The minimum
time cycle is 30 seconds to one minute. The rectifier is set at
6 to 9 volts so the amperes per square foot is at a minimum of
10 to 20 A/sq. ft.
There are many commercial products for the electro clean solution.
If you need more on voltage, I could see if I can find it
for you. What I usually do is use a stainless steal tank that was
originally designed for developing 35mm film as the anode and the
silver as the cathode. I usually make my own solution with TSP, and
use a variable voltage supply at a voltage high enough to give me
bubbles.
A commercially prepared electro clean solution that I have yet to
open, instructs you to heat the solution to 180 degrees F, pour it
into a clean glass container and apply 10 volts for 60 seconds while
agitating, using a stainless steal anode, and NOT to reverse the
current. The glass is a good idea, it is very easy to short the
jewelry to the tank I use, especially long chains - I sometimes line
the tank with filter paper to avoid shorts. It works great to remove
the sulfur blackening on sterling chains.
Does anyone know how to remove the oxidation from white bronze after
having enameled it? Regular pickle doesn’t remove it and only heavy
clean up with abrasives seems to do the trick which is way too time
consuming for large production.
Have you tried Nickel Pickle? It’s a mixture of Hydrogen Peroxide and
Borax…I can’t seem to find a recipe but as I recall it’s 1 cup
hydrogen peroxide and 1 teaspoon or tablespoon of Borax. Works great
with nickel and other metals that have stubborn oxidation.
Have you tried Nickel Pickle? It's a mixture of Hydrogen Peroxide
and Borax...I can't seem to find a recipe but as I recall it's 1
cup hydrogen peroxide and 1 teaspoon or tablespoon of Borax. Works
great with nickel and other metals that have stubborn oxidation.
Borax will not work for this. What you are referring to is 3%
hydrogen peroxide and Sparex. Bill Seeley of Reactive Metals brought
this to the jewelrymaking community many years ago. In higher
concentrations it is/was used in the semiconductor industry and
called “Pirana Etch” in that case it is 30% hydrogen peroxide and
sulfuric acid and very dangerous stuff. It was used to remove all
organic contamination from silicon wafers. You can use any of a
variety of acids in combo with the 3% hydrogen peroxide fairly
safely. I have used sulfuric, or citric acid as well as Sparex and
have seen reference to lemon juice or vinegar. In any case it will
remove copper oxides and etch copper but will not necessarily leave
the surface chemically clean. In fact all the methods that have been
suggested in this thread leave some traces of themselves on the
surface either as reaction products or just remnants of the cleaning
methods. The real question is what is clean enough for your needs and
once you know that you can set about achieving that. A couple of
posts have referred to the water sheeting rather than beading up this
also can occur even if there is a significant amount of detergent
left on the work. Detergent and other surfactants will cause the
sheeting action.
So to the original poster what is the application that you need to
have “chemically clean” metal for?
So to the original poster what is the application that you need to
have "chemically clean" metal for?
That would be me. I color the brass pieces I make by alternately
dipping them in sparex and liver of sulfur. Sometimes the results
are spotty, and I noticed the the water was beading off, which I
thought might indicate that the metal was not clean enough to color
evenly.
That would be me. I color the brass pieces I make by alternately
dipping them in sparex and liver of sulfur. Sometimes the results
are spotty, and I noticed the the water was beading off, which I
thought might indicate that the metal was not clean enough to color
evenly.
Previously mentioned but worth repeating, a brass brush and pumice
powder will prepare a surface for liver of sulfur. I like Fast Orange
hand cleaner, it has a de-greaser and pumice and I can always use it
to get tripoli or rouge off my fingers quickly when I have to go
quickly go retail
That would be me. I color the brass pieces I make by alternately
dipping them in sparex and liver of sulfur. Sometimes the results
are spotty, and I noticed the the water was beading off, which I
thought might indicate that the metal was not clean enough to
color evenly.
I would make sure I neutralized the sparaex by rinsing in water and
baking soda followed by a clear water rinse. Sparex is acidic and
liver of sulfur is alkaline so you are probably not doing your
patina process any good if you still have sparex residue on it when
you go into the liver of sulfur.
For a patina clean by using a small amount of dishwashing detergent
(Dawn or the like) in water and a fine pumice powder on a washout or
tooth brush or your fingers to clean the work. Follow with a rinse
in clean water. I use bottled water as a rinse just to make sure it
is clean enough.
A couple of posts have referred to the water sheeting rather than
beading up this also can occur even if there is a significant amount
of detergent left on the work.
Absolutely. Part of their action is to reduce the surface tension of
water and therefore “wet” the surface of the object to be cleaned
(the “sheeting” as described). Detergent molecules, which are
surfactants (SURFace ACTing AgeNTs) work at the interface between oil
and water (as well as at the water/air interface). Their hydrophobic
tails which dissolve in oil but don’t “like” water group together,
while their hydrophilic heads dissolve in the water, forming a sphere
(micelle) around the oil droplet. The water is then able to wash
away the dissolved oil.
The “sheeting” on the metal’s surface is more than likely due to the
presence of whatever detergent has been used, as had it been rinsed
completely, the water would revert back to beading up, having
regained its normal surface tension.
I would make sure I neutralized the sparaex by rinsing in water
and baking soda followed by a clear water rinse. Sparex is acidic
and liver of sulfur is alkaline so you are probably not doing your
patina process any good if you still have sparex residue on it
when you go into the liver of sulfur.
Actually, just the opposite. I did a lot of experimenting, trying to
get brass to respond to liver of sulfur. AFAIK, liver of sulfur is
not even recommended for brass. I get the best results by first
pickling the piece in hot sparex, then mixing up a batch of liver of
sulfur in hot water, then dip the piece in LOS, then directly back
into the sparex (I do this outside, to avoid the concentration of
toxic fumes). I repeat this process at least three times to get
desired coloration. It gets darker each time, but the darkening
occurs mostly while it’s sitting in the sparex. I suppose if I
repeated it enough times, the brass would be almost black. I throw
out the liver of sulfur solution when I’m done; it gets ruined in
the process, but the sparex doesn’t seem to be adversely affected.
The "sheeting" on the metal's surface is more than likely due to
the presence of whatever detergent has been used, as had it been
rinsed completely, the water would revert back to beading up,
having regained its normal surface tension.
That’s good to know, but also disappointing, since I thought that
was an easy way to judge the cleanliness of the metal. I’ve been
experimenting with different things at home and found that a soak in
a solution Oxy-Clean produced the sheeting effect. How long would I
have to rinse the metal to know if the results are positive or
negative?
Why don’t you just use gun black (or it could be called gun blue)
from any gun shop? It colours black on all brass and bronze and very
easily. It works just like LOS but you don’t have to mix it up and
can use the liquid for years as long as you close the bottle tightly.
That's good to know, but also disappointing, since I thought that
was an easy way to judge the cleanliness of the metal. I've been
experimenting with different things at home and found that a soak
in a solution Oxy-Clean produced the sheeting effect. How long
would I have to rinse the metal to know if the results are
positive or negative?
Here’s my question about this issue: I use only a slurry of pumice
and water to clean metal before etching. Presumably, there’s no
“detergent effect” in that situation. I still judge the metal’s
cleanliness by the sheeting effect. Am I missing something here?
Here's my question about this issue: I use only a slurry of pumice
and water to clean metal before etching. Presumably, there's no
"detergent effect" in that situation. I still judge the metal's
cleanliness by the sheeting effect. Am I missing something here?
Judy, Judy, Judy…no you are not missing something. I use Fast
Orange…because it is in a pump bottle. It does have detergent and
pumice in suspension. Best of both worlds. A brass brush and 10
seconds seems to do the trick, just rinse well. Just pumice and
water will work fine as you well know.
Here's my question about this issue: I use only a slurry of pumice
and water to clean metal before etching. Presumably, there's no
"detergent effect" in that situation. I still judge the metal's
cleanliness by the sheeting effect. Am I missing something here?
The “wetting” of a surface is measured by the contact angle of a
drop of the liquid on the surface. If the contact angle is less than
90 degrees then the drop looks like a hemisphere or a low dome. If
the contact angle is greater than 90 degrees the drop starts to
approach a sphere in shape. By creating a rough surface you will
lower the contact angle between a liquid and solid. A low enough
contact angle results in the sheeting action that has been
erroneously assumed to mean that the surface is “chemically clean”.
The beading or sheeting of water on a metal surface is influenced by
many things such as the presence of surfactants or other materials
that act to reduce the surface tension between the water and metal as
well as how smooth the surface is. On a highly polished surface even
if it is extremely clean water will bead up. On a fairly contaminated
surface if it is textured you can get the water to sheet. This is why
the sheeting of water is useless to determine cleanliness. Your
pumice cleaned surface definitely has left some pumice embedded in
the metal, is that perfectly clean? No way, but the pumice will not
interfere with patinas and in fact the slightly rough surface will
generally enhance the depth of color and adhesion of the patina. So
scrubbing with pumice is not really just a cleaning operation but is
also a surface preparation operation that is beneficial to patina
application. The pumice can and indeed does remove oxides and dirt
but it may only be partially effective at removing oils. Combinations
of pumice and detergent will remove most foreign matter but will
leave some pumice behind embedded in the metal surface and if it is
not rinsed enough will also have detergent residue on the surface.
