Friday, January 17, 2014

Friday Progress

Burned out the shells last evening. Inspected the ceramic shell and found two that had hairline cracks. Some furnace cement and will let them cure over the weekend and cast them next week. Cast the figures today. Between the two of them, they used 40 pounds of metal. I did not have sufficient metal left in the crucible for the other two molds. I decided not to get greedy and do another heat. Will cast those two with the repaired shells next week.

Here are the figures.
Pushing Guy

Pulling Guy

Pushing Guy mostly decanted

Pulling Guy partially decanted

Tentacles on both came out great

Two hours on after the pour, and the metal figures are still uncomfortably hot to the touch.

I still, after ten years, have a lot to learn about rigging.

I'm getting casting defects that would not be there had I rigged the pieces properly. Both pieces suffer from shrink porosities, where the cooling metal collapses as there is no replacement feed from the rigging. Shrink bobs - large masses on the runner near the gate to the piece - would have ameliorated this defect somewhat. As it is, both of their asses looked like they got chewed up badly.

Either shrink bobs, or I need to add more runners. I hesitate to do this as it means more work removing them and cleaning up the surface where they were attached. But the amount of welding and grinding I will do to fix the defects turns out to be the same amount of work of removing the extra runners. I just have to get used to sacrificing the piece to make the sculpture, like killing the book to make the movie.

The other problem is I rushed dipping the pieces before the slurry was completely mixed. As a result, there were millimeter-sized bubbles like little zits that are now on the surface. I've dealt with this before. They are easy to remove, but waiting an extra six hours would have eliminated this problem, and I still would have been able to cast them today.

I really should keep notes on all this.

No comments:

Post a Comment