Preparing mold for Aluminium casting

After we came back for our second term we had to decide whether we’d prefer to work with Wood and Metal or ceramics and Glass. I decided to work with Wood and Metal where I will learn how to lathe,  create a mold for Aluminium pouring and wood laminating with veneers.

We were given polystyrene to create a form we would like to cast in Aluminium and I decided to take advantage of the textures in the polystyrene and create quite a rustic cube, hopefully I will be able to experiment with the reflection of light inside the aluminium cube.

To start this process we had to mix our sand, which will form the mold for the Aluminium. We mixed high Silica sand with sodium silica, when the sand reacts with CO2 it hardens creating a perfect mold for Aluminium.

Using mdf we created a box to hold the sand and started to fill the edges around our polystyrene, each layer had to be patted down to make sure it went into every crevice. Using a drill we created small air vents at the side of the mdf then pumped CO2 gas in, it will take a couple of hours for the sand to set so it’s best to leave over night.


After the sand is set, remove the mdf and flip the block over, create higher walls around the block of set sand so we can finish the bottom of the mold where the aluminium will be poured through. Cover the sand with baby powder then continue to add sand on top until it’s full, then pump CO2 to set the sand and wait an hour.

Both layers should now be free to separate. You will need to create a pouring hole, I created mine by making a cast of a plastic cup then drilling a hole down from the bottom of the cup, through the top lid through to the polystyrene, make sure to create some extra air vents to the polystyrene as well.

This is how your mold should look like, here you can see the polystyrene through the pouring hole. Once it’s ready glue all the layers together to make them secure and leave to set until the aluminium is ready.

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