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Homemade Bronze clay FAILURE! Any ideas what I'm doing wrong?
Good Morning!
I'm new to metal clay, and experimenting.
I tied to make my own bronze clay, and it was a dismal failure. I'm hoping the people here can help me figure out why!
Ingredients (I live in Germany, so sorry for the German language pages :
Bronzepulver, atomized
Grain size: 44 microns (325 mesh) irregular
Melting point: 1083 ° C
https://www.amazon.de/gp/product/B01...?ie=UTF8&psc=1
Methylcellulose
100% pure methyl cellulose E464 Nutritional information: Suitable for vegans and vegetarians, GMO-free, suitable for halal food.
https://www.amazon.de/gp/product/B01...?ie=UTF8&psc=1
Recipe:
~3 parts bronze powder (3 'scoops')
~1 part methylcellulose (1 scoop)
- Distilled water to powdery clay
- Massaged with olive oil until workable consistency
Molding clay. :
- Made a number of my usual 'test coins'…a small disk about the size and thickness of a quarter…imprinted with a simple pattern.
- Dried at ~100°F for about 6 hours. Then left sitting overnight at room temp.
Firing and results:
I fired the clay with three attempts. Each coin separately.
1. First coin.
Fired using the same technique for store-bought PMC3 bronze clay.
- Large butane torch
(https://www.amazon.de/gp/product/B00...?ie=UTF8&psc=1)
- 8 minute timer.
- Burned off binder for ~1 min
- Sintered at nice, cherry red glow for 7 mins.
- Immediately cooled in water (dropped in room temp water)
- Results: See image one. Coin crumbled like ash No discernable metal sintered.
2. Second coin.
Fired using significantly higher heat.
- Large butane torch
- 8 minute timer.
- Burned off binder for ~1 min
- Sintered at bright orange glow for 7 mins.
- Immediately cooled in water (dropped in room temp water)
- Results: See image two. Most of coin disintegrated during sintering. INTERESTING NOTE: Little balls of molten bronze bubbled to surface. Edges of coin appear to have sintered.
3. Third coin.
Fired using significantly lower heat.
- Small butane torch (https://www.amazon.de/Melting-Brazin...c+butane+torch)
- 8 minute timer.
- Burned off binder for ~1 min
- Sintered below any observable heat glow for 7 mins.
- Immediately cooled in water (dropped in room temp water)
- Results: See image three. Basically, the same as one. Coin breaks in half easily (easier than breaking the dried clay before hand )
SOOOOOOOOOO!
ANY IDEAS WHAT I'M DOING WRONG? WHAT I CAN CHANGE?
Thanks!
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I have to say from the outset - I've not tried this and don't work with clay, but kudos for giving it a go.
My immediate thought is that your butane torch may not be putting out quite enough heat for sintering - the instructions I've seen for torch firing home-made clays say to look for a shimmer. Can you surround the test pieces with firebricks to slow down the heat loss? Also, is there any mileage in oven-drying the pieces to drive off any remaining water?
There's a number of recipes & ideas here - http://www.metalclayacademy.com/meta...etal-clay.html
Most of them seem to be kiln-firing for 1 hour for the binder, 2 hours to sinter. I've no real expectation that the DIY clays will respond the same as commercial ones.
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The torch can get up to about 800°C and, on the second test coin, I think it was too hot. The torch at 7 mins is the firing method I use for the commercial metal clays.
I am curious however, if the solution for non-commercial metal clays is; lower temp for longer. Maybe in a kiln.
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I was interested so I had a look on youtube the guy also has some other videos on mixing etc
Last edited by josef1; 03-03-2017 at 02:20 PM.
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Thats awesome. Actually, that's where I got my recipe (Actually https://www.youtube.com/watch?v=rXfrOrz2cB8)
He's using a kiln and I'm using a torch. I'm very curious why the PMC3 commercial bronze is very easily torch-able, and this isn't.
Although, watching that link again, I looked up my Bronze powder and it is recommended for cold casting (although I can't get the metal content on it).
I've ordered some different powder from another manufacturer (who does list the content). Maybe it will be better?
I'll keep the thread posted
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If it's for cold casting, is it definitely bronze and not a coloured aluminium powder?
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