About the Lost Wax Process

Although an ancient practice, the lost wax

process today may vary from foundry to foundry. 

However, the steps which are usually used in

casting small bronze sculptures in a modern

bronze foundry are generally quite standardized.

Here at WH Casting we use a very unique vacuum

cast machine.  This one-of-a-kind casing

machine was originally built specifically for

NASA.  We acquired it in 2009.
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                              What sets us apart in the casting world is the fine tuned                                                        precision pours under pressure and vacuum this machine provides.                                    Other foundries use the older technique of having to create a shell of                                  investment slurry (a plaster of Paris type solution) around their waxes                                  and then after the wax is melted out they use giant vats of molten                                        bronze to pour into the empty shell.  With our machine we don't have                                    to go through the waiting stages of a shell investment to set up.  That                                process can take upwards of a week or more to create a thick enough                                shell around the wax before the molten metal pouring can begin.  Our                                process uses specialty fit cans or flasks that are built specifically for                                    this machine.  These cans are filled with as many waxes as we can fit                                at a time and then our investment is poured around it, filling the can.                                  We also vacuum the invested cans in their liquid state to help eliminate any air trapped around the wax.  The slurry content of these cans set up in about an  hour and can go directly to into the Burnout oven.
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The other  difference with our process vs. the standard casting method is that we only melt enough bronze at a time to cast exactly what we need for each can.  By weighing out the wax weight and using a conversion code we can determine the exact amount of bronze needed for each can.  What really sets us apart is the fact that once the door shuts on the casting chamber vacuum begins and nitrogen gas is introduced to create a completely inert, pollution-free casting environment resulting in perfect castings.

After the bronze drops into the can it can almost immediately be removed and set aside to cool.  There are two methods of breaking out bronze from the investment cans: quenching or air hammer.  The air hammer is a good solution when it's too cold to play in the water outdoors.

The finishing process is quite simple around here, we do a bath of Liver of Sulfur and polish back to create a lovely natural bronze contrast.