Ok everybody here is a copy of my original paper on Hydrogen Peroxide
Pickle. I reversed engineered the process from a commercial pickling
process. It must have been about 1979 at the University of Kansas.
HYDROGEN PEROXIDE PICKLE
Heat-treating and soldering of copper and copper basedalloys can
often coat the metals with a combination of black (cupric) and red
(cuprous) oxide. The black oxide is easily removed in a standard
warm sulfuric acid or Sparex bath. This will leave a red smut, which,
with other undissolved oxides, forms a red oxide scale. This scale
readily oxidizes further, leaving a dark, nonuniform patina. It can
be imbedded in the metal during subsequent forging and drawing, so it
should be removed. Abrasive removal of the oxides can result in loss
of design details and crisp edges. This simple chemical treatment is
offered as an alternate method for its removal.
Hydrogen peroxide (H2 O2) pickle eliminates the need for abrasives,
and has the added attraction of being relatively inoffensive. The
following procedures and formulas provide for the removal of red
scale from copper, brass, bronze, nickel silver, reticulation silver
and some gold alloys. It will remove the copper coating from silver
that has been accidentally pickled in an iron contaminated acid.
Curiously, it will also remove the natural oxide layer found on
aluminum. There is a great deal of latitude in the formulas and a
variety of surface finishes and textures can be obtained.
It is suggested that you run some tests before applying these
formulas to your work. Find the procedure that best fits your needs.
When working with any acid the possibility of damaging your work
always exists. These formulas can dissolve a brass piece and leave
the silver solder seams standing.
Some points to remember when using hydrogen peroxide pickles:
Adding more acid to the solution will not improve its action. The
acid is just a catalyst or starter.
Iron and silver will tend to shorten the life of the bath. This
does not mean you cannot put these metals in the bath.
Use only sulfuric acid, Sparex or vinegar as the catalyst in
Use 3% hydrogen peroxide available in drug stores, or mix a 2-3%
solution from distilled water and concentrated H2 O2 (usually 30%),
available through a chemical supply house. More concentrated pickles
(5%) can be mixed when deep, fast etching is desired.(Warning!
Concentrated acid is very dangerous. Do not attempt without proper
training and equipment.)
Always add acid to water!
- Use these solutions warm (110F), or about the temperature of a
The hotter the pickle; the faster and coarser the etch.
The following formulas can be made up as needed, or they can be
premixed and kept for an extended time in the original brown bottle.
It can be reused until saturated (blue) and it stops working.
Hydrogen peroxide decomposes rapidly when exposed to light. The
active life of these pickles is limited to about four exposed hours.
Put your solution back in the brown bottle for storage. The acid
component of these solutions can be either measured or slowly added
until bubbles begin to appear on a sample of the metal. This signals
that the solution is active.
SOLUTION #1 (mild):
2 parts Hydrogen Peroxide (3%).
1 part water.
2-4% fresh sulfuric acid (5-10%) or Sparex solution.
SOLUTION #2 (strong):
1/2 cup Hydrogen Peroxide (3%).
1 Tablespoon fresh sulfuric acid (5-10%) or Sparex solution.
STEP #1: Prepickle the piece in standard Sparex or sulfuric acid
solution (5-10%) and rinse. All the black oxides should be removed.
STEP #2: Place the Hydrogen Peroxide pickle container in a second
bowl of hot water to keep it warm. If possible suspend the piece in
the warm pickle. After a moment bubbles should appear on the piece.
Agitate or brush with a feather to clear the bubbles. Remove the
piece from the bath every couple of minutes to check the progress. It
may take 5-10 minutes. Rinse well.
STEP #3: Use a stiff tooth brush or brass brush to remove residue
STEP #4: Pickle again in standard Sparex or sulfuric acid solution
(5-10%) to remove any remaining smut.
STEP #5: Repeat steps #2, #3 and #4 if necessary.
3 parts Hydrogen Peroxide (3%).
1 part white vinegar (5%).
Follow the steps listed for solutions #1 & #2. When the metal
emerges from the pickle, it will be coated with a thick brownish
green smut. This will flash off when dipped in undiluted white
These solutions can also be applied to warm metal with a brush and
worked into hard to get corners and intricate designs.
Long term exposure to these pickles can cause the copper to be
dissolved out of an alloy’s surface. Brass, for instance, can be
pickled until it turns bright yellow. Even the mildest of the vinegar
solutions can deeply etch if left unattended.
A deep etch will often reveal the underlying crystal structure of
the metal. Care should be taken and the process watched closely. As is
the case with all corrosive solutions, these formulas should be
handled with care and in good ventilation.
Hydrogen Peroxide pickle does not remove firescale from sterling