Steam casting uses steam to change the pressure inside the crucible after the piece has been cast to force the molten metal into the mould. I read about a variation where a dried block of wood is put over the sprue hole once the metal is poured in and the burst of flames causes the metal to be forced down into the mould. Then this summer on a hike a friend described silver earrings she’d bought that were cast from tree leaves. The process involved pouring the silver into the mould and covering the sprue hole with half a potato, the resulting steam pushing the metal down into the very fine cavity left by the leaf.
I tried steam casting first at Michael Wickerson‘s but the result was not great. We used fiber fax dipped in water and I forgot to focus on creating pressure. I’d invested a leaf but only the veins of the leaf came out. That was test 1. For test 2, I cast a square raft from a 3D printer, knocked a small hole in the bottom of the crucible once it was inverted and put a potato over it. Not much happened, so I got the leak mop and put that over the hole and that created a lot more steam. For the second raft I made a bigger hole and, using the leak mop again, got a pretty good result.
Local Clay – “FishBrush”
This piece was cast during Dartmoor Arts, Summer 2015, using clay and sand dug out of the bank of the river Teign next to the Fingle Bridge pub. I found two types of clay. One was mixed with the sand and used for the investment of the wax object. The other, a kind of grayish blue clay, perhaps the famous Ball Clay of the area, was mixed with rice husks and used for the refractory layers and crucible. The sand was passed through a rough sieve to get the larger rocks out, but was otherwise untreated. As you can see there was quite a bit of organic matter left in the material that caused a lot of flashing.
Bronze and Glass
Three wax rings supporting glass beads were invested. The luted crucible was heated and the molten bronze poured in. Some of the glass beads melted during the heating process and the glass leaked out, others became part of the bronze. This luted crucible was fired in a propane furnace.
3D Printing to Bronze
The polylactic acid (PLA) nut and bolt were printed off a Makerbot 3D printer at New Mexico School for the Arts, summer 2014, and cast in bronze to make a perfectly functional nut and bolt.