Bronze sword casting-brittle swords

Ive been casting bronze swords using a soapstone mold i carved out from a counter top. I been using 90% Copper and 10% Aluminium alloy adding the aluminium near the end of the smelting process(using only propane). The 1st sword I cast was fair but a little poroes with little pits all in it. So to make the surface smooth I tried heating the mold b-4 casting and the 2ond cast was worse than the 1st. The sword fell into 3 peaces when i separated the mold(after letting cool). Im not sure where im going wrong. Ive been thinking it may be the alloy or maybe my vent in the bottom of the mold is not big enough. I quiche the 1st sword in water but let the 2ond air cool. Any suggestions?

Wish I could help ya, I haven’t cast bronze before, but do you have any pictures of the pitting you could post and of your mold?

I’ve cast 8 or 9 now. Seems that if i lay the mold at a 45 degree angle the molten bronze pores smooth but only goes a little past the hilt and stops(looks like a good spear point though). So if i go in between 45 and vertical it’ll pore all the way but still burps and upchucks cumming out brittle. Im trying to find a balance and modify where i can.

Here is a better pic of the mold.

Here are some of my castings i haven’t re-melted yet

Hey Ryan,

Nice seeing some shots! Geez, if I had to guess, it’d be that the temperature isn’t there. That, or the % of the alum to copper is off or too many impurities within the metal itself.

I know a local guy here who does bronze pours, I’ll give him a shout to come check it out and see if he can’t help give some advice.

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