Casting Metal: Soapstone Molds – Part 4: Pouring the Metal and Perfecting the Mold

OK, so you have your mold ready, you are wearing safety equipment, and you have your metal melted. Now what? I highly recommend clamping the mold closed with something that will not burst into flame if you pour molten pewter on it. You do not need to use a lot of pressure, but the mold pieces do need to be properly aligned and held together. My most common arrangement is a couple of spring clamps that hold everything neatly in place. You can use C clamps, but be careful not to apply too much pressure to the mold, you do not want to crack it. Experienced pewterers will often simply hold the mold closed with a heat resistant glove on and pour the metal. I have done it many times myself, but one of the problems is that the mold will become progressively hotter as you pour each piece. If you are pouring a lot of molds at once, the molds will have some time to cool down, but it you are only pouring one or two molds the molds will quickly become too hot to hold and you will be at risk of dropping the mold, which could break the soapstone.

These are the types of clamps that I use.

Why clamp the mold? It allows you to keep your hands completely out of the way of the molten metal. Most people will use a small metal ladle with a spout to scoop up and pour the metal from the melting pot into the mold. Whether you are doing that, or simply pouring from the container in which you melted the metal into the mold it is inevitable that at some point you will spill some molten metal outside of the mold. That is why the surface on which the mold rests while you fill it needs to be non flammable, and you need to have your hands out of the way.

Pour molten pewter into the mold until it is full. Wait for the metal to cool down and re-solidify. If you jiggle the mold a lot at this stage you risk creating a grainy unusable product. Leave the mold alone. If you watch the metal cool you will see it go from shiny to dull. Give it several more minutes, and then open the mold. Both the mold and the casting will be HOT.

The chance that your piece will pour perfectly the first time that you try it is slim. If it does, and continues to pour well, congratulations! You have completed your first soapstone mold.

If the piece does not cast well, try again. Make careful observations. Does the casting improve as the mold warms up? Does it seem as if there is enough metal? The sprue and funnel area should be completely filled with metal. If they are not, are you pouring the metal directly into the funnel portion of the sprue? Is the metal hot enough? If the metal is too cool it will be more viscous and not flow as well.

Next Time: My Piece is Not Casting Well – What do I do next?