Bronze After Aluminum

The goal for this experiment was to pour bronze after aluminum in the same pour. I was hoping the bronze would melt the aluminum already in the mold. Unfortunately, I was a bit cautious and the bronze was poured too cold and did not have a chance to melt the aluminum to any degree.

As you will see in the pics, the bronze shrank and pulled away from the aluminum, creating little or no real mixing.

Overall, I learned a lot, but it was an expensive failure with all of the contaminated bronze and no piece to show for it. I’ll be working with the smaller egg experiments until I can make the metal work for me with consistency.

Full mold and detail of the release valve. The level of the aluminum was achieved using the same concepts used in plumbing traps beneath your sink. When the metal was poured, we knew the interior walls were coated with a thin sheet of aluminum that would mix with the bronze later.
Full mold and detail of the release valve. The level of the aluminum was achieved using the same concepts used in plumbing traps beneath your sink. When the metal was poured, we knew the interior walls were coated with a thin sheet of aluminum that would mix with the bronze later.
 After the bronze was cast the investment material was removed and some sections were polished to see if there was any less obvious metal mixing. The gating has the golden color sometimes achieved with Al-Bronze alloys, but when polished, it was basically bronze colored underneath. The pour cup remained aluminum free, but will have to be placed in scrap bin because it has some contamination. There were three defined patinas on the bronze section. I originally thought they were due to concentrations of aluminum, but polishing did not reveal that to be true.
After the bronze was cast the investment material was removed and some sections were polished to see if there was any less obvious metal mixing. The gating has the golden color sometimes achieved with Al-Bronze alloys, but when polished, it was basically bronze colored underneath. The pour cup remained aluminum free, but will have to be placed in scrap bin because it has some contamination. There were three defined patinas on the bronze section. I originally thought they were due to concentrations of aluminum, but polishing did not reveal that to be true.
 Closeup view of where the bronze pulled away from the aluminum. There was obvious mixing of the metals closer to the aluminum section. The bronze was a much lighter color, but still did not bond or mix enough the keep the piece together.
Closeup view of where the bronze pulled away from the aluminum. There was obvious mixing of the metals closer to the aluminum section. The bronze was a much lighter color, but still did not bond or mix enough the keep the piece together.