This photo shows the difference between a two-part sand mould and an open pour. The level of detail on the two part mould is far greater than on the open pour.
I had read that this was the case, but I’d not experimented myself previously.
Both pieces are ‘my-smelt’ copper with silver alloy, cast in oil sand. The piece on the right is made in a two-part mould. The piece on the left I heat-patinated after I’d cleaned it up. Both are from the same former, which is an Edwardian mourning brooch. I will make the more detailed piece into a necklace; the open pour piece is too heavy to wear, but is very tactile.
The second casting that I did with my first-smelt copper produced the ‘Manx cat’, a mouse, a pudding charm of the Christ child and two partial shells.
The mouse and the pudding charm were the more successful pieces. I have ordered a different kind of casting ring for the shells, to see if that is more successful. The shells are too fine for a conductive metal like copper, which tends to cool before completing the mould.
It is exciting using metal that you have ‘made’ yourself.
Some of the copper that I smelted at the Sculpture workshop was not very pure. By hammering it I was able to get rid of much of the impurities ready to alloy with silver and melt for casting. I think that this was the first time that I used this blacksmiths hammer and my rather rusty anvil/
The New Year bonfire was the first trial smelt of the year. I didn’t expect much from it and it wasn’t a great success, because the bonfire dropped through into the rock pool beneath it. It seemed a good way to celebrate the New Year though.
The photo is the wet remains when the bonfire had burnt out, a gift to the sea.
Following further research I have made up some clay balls with a mixture of malachite and charcoal inside to smelt. Copper results from removing oxygen from the copper ore, so the sealed clay balls should be more successful that the pit smelt that I did at the Sculpture Workshop.
I like the way the clay balls look a bit like poppy seed heads.
I’ll let them dry out a bit before I try and get them to smelting temperature in a charcoal furnace.
I have been awarded funding for my Stone to Bowl project. It will pay for several weeks at the Scottish Sculpture Workshop in 2018 to complete the project which will take copper ore through to cast pieces, using traditional and fully sustainable methods.
I’ve been doing some preparatory work:-
I experimented with melting the copper that I pit-smelted this year at the Sculpture Workshop, adding in some silver to lower the melting temperature. I melted 115gm and got 74gm of copper and some residual oxides which didn’t melt. The left hand metal is copper, the right is the original smelt material which is less pure. Next trial will be to sand cast with the copper/silver alloy.
The second ‘hole in the ground’ smelt produced copper in pellets, it was probably just a smidge too cool, but pellets will be super handy for casting.
We did a third smelt, but I don’t have photos as yet. It produced more consolidated copper at about the same ratio of ore to metal.