How To Make Better Mistakes: Aluminum Casting No.4

After our last attempt at aluminum casting, we decided that what we needed to do, finally, was to make molds with proper venting, to allow the hot metal to enter more easily and fully. So we did that.

[ some different vent/pour configurations, including a 'simian Venus' model ]

We made the figures and prepared the molds for plaster.

Then I burned out the molds in the toaster oven for about 3 hours, at a nice even temperature of around 125 degrees, so all the wax poured out and it didn't burn or stink too badly.

And then we decided to put everything in the kiln as we had done in the last session, so the molds would have the same temperature as the molten metal.

Except that we realized that we hadn't mixed the plaster with sand, so would it survive such high temperatures? It was just plain old Plaster of Paris...

The answer? No.

All the molds cracked.

We had also forgotten to design the molds as we had previously, with a spot for an aluminum ingot to sit and melt and pour into the void all by itself. So we tried to cast the metal anyway, and it either poured out the cracks...

...or else it seemed to not even make it in!

We also noticed that the molds still had wax in them.

wax remnants caught fire

wax residue on the ground

And then I remembered that my friend Tamas at Mikebuda Park of Study and Reflection in Hungary had told me that they always melt out the wax for a few hours at a low temperature, and then for a few more hours, much hotter, to really burn every last little molecular bit out.

For me, the whole experience was a great example of learning. Or rather, of how hard it is to learn. People say that you learn from your mistakes but they don't tell you that you need to make the same mistake over multiple times before any real learning happens. That's my experience anyway.

[ mutant yoni lingam (above) and who knows what this was? ]

Sure, we had learned that the best way to cast these objects would be with vents, but we forgot that plaster won't withstand 660 degrees without sand in the mix. And we also forgot to add ingot-pour holes in the design of the figures to be molded.

[ the tail-vent came out, but no head! ] 

But still, against all odds (the beauty of the fire craft, and another great lesson in itself!), we got one nice surprise:

One Venus worked fine! Work to be done to finish it off now, of course, but it's all there in glorious aluminum!

So, note to selves: next time remember to
- add sand to the plaster mix
- make molds with pour holes and vents
- burn out the wax from the molds longer and hotter

And perhaps all will work out perfectly. Or not. But our goal is to at least make better, more interesting mistakes.