Tips for Carving wax 2. Lost wax
Casting of your carved wax Ring.
By Jason Bellchamber
Lets go through the steps to create a
simple ring design with a pattern going around the band. Iíve decided
on making a design from an art history. Itís a symmetrical pattern that
goes all the way around the band.
1. I decide on the thickness of the
band, in this case 7mm and cut a section of the wax tube 9mm wide using
a coping saw.
2. Then I ream the inside of the tube
out to the exact finger size I desire, on a mandrel or, in this case my
own finger. This is the only time you should try the ring on a finger.
Once the walls of the ring are less than 2mm thick, it becomes very
3. Then I use a rasp or very coarse
file to bring the edges of the ring down to a thickness of 1.5mm. I
like to make the thickness uniform; it makes for a more comfortable
4. Once the desired thickness is
achieved, I then turn to a finer bastard file to make the edges smooth
so that no scratches are visible. Now the fun begins! We can start
carving our design into the wax.
5. As recommended if this is your first
attempt keep it very simple, or even plain, that way you will get a feel
for carving the wax and then polishing the cast metal piece. I have
chosen a pattern that repeats itself every three steps, itís called a
Triskele. I begin by using a compass to lightly score the lines where
the pattern will repeat itself. Then move to a ball burr (or empty
mechanical pencil end) to mark the pattern in dots. Then I connect the
pattern using the mechanical pencil scoop.
6. Once the pattern is carved
completely, and Iím satisfied, I decide what metal to cast it in. In
this case I decide to make Sterling Silver. Sterling silver is
traditionally 92.5% Silver alloyed with 7.5% Copper. Fine silver can be
purchased at pawn shops or coin stores in 1 oz. wafer or coin form.
Pure Copper can be had from old pipes and fittings.
7. Weigh the wax on a scale to a 10th
of a decimal. Multiply the wax by the specific gravity of the metal you
are casting with. In this case I use 10.5 x weight for Sterling
Silver. Add another 10gms final metal weight for the sprue base. This
excess metal will push all of the molten metal during the cast into the
8. The first part of setting up a wax
is to attach/melt a sprue to the ring in order for the molten metal to
flow into the hot mold. The sprew attaches the ring to the Base of the
mold and provides an opening for the metal to flow into. The sprew is a
1.2-2mm round stick of wax that should be a max of 1.7cm long.
9. Once the sprew is attached to the
ring the other end is melted onto the Rubber sprue base.
10.A steel flask is placed onto the
mold so that the piece to be cast sits basically in the center of the
inside space. A special plaster commercially known as investment is
mixed with water and poured over the wax and fills the flask. Once it
is prepared and hardened it is smoothed at the top and the rubber base
is removed from the mold. Now the wax sprue is the only part visible.
11. The flask Is placed in a Kiln and
slowly heated to 1350 degrees and held there for 1 hour. This nearly
gurantees that all the wax is melted or at least sublimated inside the
investment. The Temperature is lowered slowly to the proper casting
temperature ~900 for Sterling Silver.
12. In this case we are using a
Centrifugal casting arm which uses a spring to spin. The centrifugal
action quickly forces the metal into the flask. Before the modern era a
cuttlefish bone mold was used on the end of a chain and spinning it by
hand would force the metal into the mold.
13. The Metal is metled into the clay cruscible which takes less than a
minutes. ONce it is completely melted, the hot flask is quickly removed
the oven and placed in the centrifugal arm. The pin is dropped and the
spins the liquid metal into the mold. The visible part of the metal or
solidifies first since it is the only section exposed to the air. The
actually takes about 10 seconds to solidify if it is silver or gold.
arm stops swinging the flask is allowed to cool for ~10 minutes to
guarantee uniform solidifying.
14. When ready the flask is immersed into a bucket of water and the
, explodes off into the water, leaving your metal casting.
12. Clean off the investment from the casting and use a jewellers coping
cut off your piece from the sprue. The Spure can be used over with newer
material next time you cast.
13. Now you are ready to follow the steps in hand polishing your peice.
a rough bastard file on a wooden surface, cut the sprue down to the
the ring. Next use your rough sandpaper to clean off the oxidized layer
inside and outside of the ring. Next step is using your fine sandpaper
smooth off any scratches. I find when finishing the pieces by hand that
grit of the smoother sandpaper comes off and the paper underneath
shiny finish. For a final polish on the cheap I suggest getting the
paper towel you can find, ie. the industrial brown stuff they use in
it makes an excellent final polish. It's at this point that the surface
to gleam and you are finished. In all set aside 3-4 hours to hand
finish your work.
Your initial few pieces
should be finished by hand because it will provide you with a feel for
the metal that you are polishing. Metal has a aura of being hard, but
when you get a sense of each elements malleablities and properties you
will see which one you prefer.
All photos by Jason