Making the Wax Impression
The wax used in foundry work is a special kind of wax called microcrystalline wax. It is available from various suppliers, but I like Kindt-Collins "Victory Brown". It is a softer wax and has the ability to easily stick to itself. It is the most common wax used in the art foundry. It is suitable for painting up the wax or slush casting. One must take wax compatibility into account for the foundry's sake. We don't like to mix waxes as most of it is reclaimed. So much for the misnomer "lost wax". Consult your foundry for more information on their wax recommendations.
First you must acquire some equipment for basic wax working. I want to stress this: WAX IS HIGHLY FLAMMABLE. Microcrystalline wax is a petroleum byproduct and at it's flash point (around 600F depending on the wax) it will burn like diesel fuel. I burnt down my studio from a wax fire and almost died in the process. It was gone in a matter of minutes. Water only makes it worse and many fire departments do not have the proper chemical . USE CAUTION when melting wax. I use commercial food warmers that will only heat to just above 212F. They can be bought at commercial food suppliers. Always use a water bath type melter. IN the US, Hamilton Beach makes a roaster that allows use of water around the pan. Slow cookers also work if you use extreme caution. Steam tables are also good wax melters. Commercial wax melting posts are available.
A few good paint brushes and some old pots and cans round out your melting rig
Painting up a mold with wax.
Here is a shot of the first coats of wax being painted into the WET mold. Wax will not stick to wet plaster so always make sure it is moist. Additional mold treatment includes a coat of mold soap for better release, although this is not really necessary. The first coat is applied quickly and with overlapping strokes to insure good surface detail and minimal bubbles. That's me in the picture.
I continue to paint wax into the mold. Try to work quickly so the wax will not get too cold to get a good bond with the next coat.
Working up the sides of the mold. Note the overlapping strokes.
Keep painting up the wax until a thickness 0f around 2mm to 3mm is formed. As the wax cools in your paint pot, it becomes thicker and you can usually build to this thickness in 2 or 3 coats. Move on to the next step before the wax cools. If it does you can warm it with a hairdryer or heat gun.
Next-Adding a wax framework and building to a final thickness .
