(also called bonded metal
) is a casting process
for making models
, and other sorts of casts
appearance of metal
. Unlike other casting processes (such as lost wax
), cold casting doesn't involve the high temperatures required to
melt metal. Instead, powdered metal
is mixed with urethane
. The resin
is poured into a mold
where it hardens
and bonds the powdered metal together. The object can then be polished
, or have a patina
When used to create bronze statues and casts, this process
is called bonded bronze.
It may take a few experiments and tries before you have success with
cold casting. To get started, I'd recommend first trying to make a
urethane cast without the metal powder. Make a mold of what
you'd like to cast with Smooth-On Smooth-Sil 901, which is easy
to work with.
For pouring into the mold, Smooth-On Smooth-Cast 300 or
Smooth-Cast 325 Colormatch are good urethane resins
to start with. The Smooth-Cast 300 may be easier to find in stores
and cures to white. The Smooth-Cast 325 Colormatch is a
color-neutral clear amber so works better for cold casting. To use
these, mix the resin and hardener 1A:1B by volume and then pour
them into the mold. Without any additives, this will give you
a paintable and sandable surface. If you want to cold-cast,
mix the powdered metal into the B part before mixing in the A part.
You may also wish to add a small amount of coloring to give more depth.
You'll want to experiment with ratios, but it will probably end up
being something like 1 part A to 1 part B to 9 parts of powdered metal,
All of these (the powdered metal and the Smooth-On products)
should be available or orderable by your local craft store.
Be sure to follow appropriate safety precautions (such as eye
protection, hand protection, long-sleeve clothing, and good
ventilation) while working with these products. Read the
material-safety data sheets before beginning to work with them!
When working with powdered metal, you should be aware that some
powdered metals are highly flammable/explosive, and are also
probably not things you want in your lungs.