Project Video - Mixed Metals Pendant with Aureus Bright Bronze and Cyprus Copper Clay by Karen Trexler
Greenware and Dry Construction
In its greenware state, the clay is slightly flexible and carves
easily. Air drying the unfired clay or greenware without heat
will reduce the potential for warping as the clay dries. Once
completely dry, the greenware should be handled with care
as it can be fragile. It is much easier to sand and refine the
greenware at this stage than to refine the metal once sintered.
When joining pieces, create a paste slurry at the join with
water, then compress both pieces together for 30 seconds.
Put aside to dry completely. Metal clay must be completely
dry before firing.
Cubic Zirconia, lab created gemstones, Nano gems, bezel
cups, and other findings or embeddables can be co-fired with
Aureus Bright Bronze Clay. Please refer to our Gemstone
Firing Guide for a comprehensive list of gemstones that are
compatible with the firing times and temperatures of Aureus
Bright Bronze clay. Most, but not all, CZs, Nano gems, and lab
created gemstones can be fired at 1400°F/ 760°C for 2 hours.
Aureus Bright Bronze Clay requires a two phase firing. The first
Phase completely burns out the binder, which helps the work
sinter properly in the second phase. Many kilns fire hotter or
cooler than their digital read-outs state. It is a good idea to
test your kiln for temperature accuracy. This can be done with
a hand-held digital pyrometer.
Full ramp to 650°F/ 343° and hold for 30 minutes
-Option 1 Arrange greenware on a mesh firing rack. Additional
pieces can be stacked using more mesh firing racks separated
with kiln posts. Raise the mesh firing rack(s) off the kiln floor
with a few more kiln posts for air circulation.
-Option 2 The greenware can be placed on top of 1” of activated
carbon in a steel firing container. Do not add activated carbon on top of the greenware for phase 1 firing. Laying flat can
create little indents because bronze gets soft while sintering.
Best to lay flat pieces vertical in the carbon.
Note | A slower phase 1 firing is needed for any piece that has
areas that are 3mm (12 cards) thick or thicker. Ramp 300°F/
149°C hour to 600°F/ 315°C and hold for 15 minutes.
Full ramp to 1400°F/ 760°C and hold for 2 hours
Once the greenware has cooled enough to handle after the
first firing phase, gently transfer the work to a kiln vessel,
such as a steel firing container that has at least 1” of activated
carbon spread on the bottom. Arrange the pieces with at least
˝” of space between them. Cover all pieces with at least 1” of
activated carbon. Additional work can be added in layers as
long as there is 1” of activated carbon above and below each
piece. Fire with a slotted lid or lid ajar. Do not cover firing
Coconut Carbon is recommended. Coal Carbon will also
produce successful results. Magic Carbon is not recommended
for use with Aureus Bright Bronze Clay as it may complicate
the use of embeddables, bezel settings, and repairs, causing
an increased or uneven shrink rate. It may also increase the
shrink rate of the clay. We recommend creating a small test
piece and fire per the schedule before committing complex
work to firing.
During firing, this clay shrinks 10-11% as a result of the organic
binders burning off (phase 1) and also the sintering process
Finishing and Polishing
Once firing is complete, it is best, but not necessary to let the
work cool completely. Place a mesh firing rack over an emptysteel container. Poor the contents of the fired container
through the firing rack into the empty steel container to
retrieve the sintered bronze. The metal can then be polished
using a wire brush, rotary tools, a tumbler, or other polishing
To Achieve a dark result from Liver of Sulfur (LOS) or Cool
Tools Patina Gel, ensure that the work piece is absolutely
clean by soaking and then brushing with hot water, soap, and
ammonia. Using a strong solution of LOS in very hot water,
dip or soak the solution until the desired darkness is achieved.
Adding a teaspoon of ammonia to the LOS bath can also help
achieve a darker result or, possibly, a rainbow effect. After
the desired patina has been achieved, thoroughly rinse your
piece to cleanse it of all remaining LOS to halt the patination
process. Then, either by hand or by machine, bring up the
high points with a polishing cloth, Scotch-Brite pad (satin
finish), or polishing wheels (high shine). If desired, protect the
patina with a coat of Everbrite™ Protecta Clear® or Permalac
Once fired, this bronze clay is metallurgically just like other
bronze metals, but, like other fired metal clays, it is more
porous than sheet stock or cast items. Due to this porosity,
this bronze clay will “soak up” solder. When possible, prepare areas for soldering by burnishing to close the open pores and reduce the tendency to absorb solder. Join other metals and
findings to fired bronze clay by using the same flux, solder, and torch(es) as you would to solder other bronze products.
Unused clay can be placed in plastic wrap and stored in a Cool
Tools Clay Hydrator to keep it moist.
Unfired clay can be rehydrated. Large dried pieces can be put
into a heavy plastic bag and hit with a mallet to break up the
pieces. A dedicated coffee bean grinder can then pulverize
the smaller pieces back into a fine powder. It is recommended
to wear a dust mask when working with any kind of powder.
Pour the desired amount of powder into a small bowl. Add
7 ml distilled water for every 50 grams of powder, then stir.
Transfer the clay to a lightly oiled plastic sheet such as a sheet
protector. Fold the sheet over, then flatten the clay with a
roller. Do not over wet the clay, but do add another spritz of
distilled water if needed. If you do over wet the clay, put it
aside until some of the water has evaporated. Continue refolding the sheet and rolling until the clay is lumping together and no longer sticking to the plastic sheet. Either lightly oil
your hands or use vinyl gloves to further knead the clay into a well-mixed lump. Now it’s ready to use!