What I’ve been up to: Bronze casting in Hong Kong

Modeling wax on top of base wax coat (photo by Jim Racine)

You wouldn’t associate this moloch of a city with the fabulously ancient art of bronze casting … in the open between former pig-sties, accompanied by about 19 really annoying tiny biting midges (note to myself: do not go for 3/4 length trousers again, as midgies love ankles). The sculptor Jim Racine runs a small studio in the New Territories and teaches courses. (subscribe to his Facebook site if you want to know about upcoming courses in Hong Kong)

I made a core from core material, which is a bit like plaster work… and of course I overworked that material too, just like I usually do with plaster. Then it becomes a bit brittle/flaky and isn’t as strong as it should be.It was very tricky to model something with a spatula. So the head came out – well – not a great piece of art but surely a good piece to learn. I just modeled without a model. The upper head turned out way too big:  the hair sits on his head like a Russian shapka. Next time I will do a clay model and make a cast of it as described in lesson 8, I think, from the OCA Sculpture 1 course. That will give me more time fine tuning the model.

Afterwards we dipped it in hot wax forming a layer of about  2mm thickness. Then I modeled a different coloured wax on top of that coat, as ideally you should reach about 4mm thickness. I think in some spots my wax layer was a bit too thin, as the molten bronze later had trouble to fill the mould evenly and left some holes, which later have to be welded and mended, which is a hell of a lengthy work process – especially if you consider that it has been avoidable to some extend by really taking care of the wax thickness at this early point. It would have been so easy…

My wax head with wax tubes and wax funnel attached, waiting to be coated with shell material

Then we built and attached an intricate system of wax tubes, so that later the molten bronze can go in and the air left in the mould can escape. There is also a wax funnel shape connected to the tubes into which the bronze is poured later. This bit will just be cut off later when the piece is cast. But we need that for the bronze to flow into the mould evenly.

Dipping the wax covered core several times into a liquid, then to be dusted with ceramic grog to form an outer shell

But for the bronze to be held both from the inside and the outside you need the outer shell, which you will get by dipping it into a liquid, which is then dusted with ceramic grog of varying coarseness. This has to be repeated over the course of a couple of days – about 6-7 times, with drying time in between.

Then the wax piece sandwiched by an inner core and an outer shell material (held together by 4, 5 pins) needs to be heated, as you need the wax to drip out and leave a gap for the bronze to go in. That takes about an hour and in the end the red glowing mould is transferred to a sand bucket, in which it is buried, with only the casting funnel sticking out.

Taking the red hot crucible (the pot with the molten bronze) out of the mini furnace

Removing the floating impurities on top of molten bronze

The casting itself was a bit too hot and needed an expert hand, so Jim did that with his wife while we watched this time.

Bronze pour into my mould, which is placed upside down in a sand bucket

Then came the moment of truth, where I had to break the outer shell with a hammer … (in the course of which I accidentally stepped on one of the pieces of that shell which was still hot enough to burn a hole into my rubber soles – all the way through! I went home in Jim’s rubber boots.)

Breaking the outer shell after my bronze has cooled off a bit, tadaa

But it’s not done yet! I have already spent a half a day cutting the tubes and welding some of the many holes my bronze head had, because the bronze hadn’t filled the mould evenly. I’ve never done welding before and my initial attempts were a bit ugly, but I was getting the hang of it after while.

Guys – if you are doing the OCA distance learning sculpture course – you really need to get some help locally. Find studios where an artist or a welder or woodworker or whoever can show you some techniques. Would I have experienced this and learnt that something like bronze casting was hard but doable on my own without Jim? Nope. But I wouldn’t want to miss it and now I slowly feel much more confident to handle the actual OCA Sculpture I course.

I’ll post the finished head when it’s done. But that may take some more time – welding and filing, then patinating…

Update January 2012: I decided I will remelt the head as it is just a bit too ugly for me to want to keep it. I rather spend the time fixing a work I want to keep.

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