16 days and counting
There are 16 days left until the opening weekend of the pavilion! We can’t believe it either. Time flies when you’re casting aluminum in cracked clay.
Last you heard from us we were busy preparing the molds for the first day of casting. The clay was dried, cracked, transferred, and glued down to the bottom of the casting trays. We cut sheetrock for the top of the molds, laid it on top of the clay, and strapped everything together as tightly as possible. We added ceramic “chimneys” to the mold to create a pour spout and ventilation locations. The finishing touch was to seal all the gaps in the mold with fire mortar.
With the molds ready to go, it was time to fire up the furnace and melt some aluminum. We went from this:
And then we poured 150 pounds of molten aluminum into our mold. And cross our gloved fingers.
The moisture left in the clay creates extremely high pressure gas which is released (along with some aluminum) through vent holes in the mold. It’s baking soda and vinegar taken to the next level. Don’t try this at home.
Believe it or not, puddles on top of the mold are good; it means that the cracks are full enough that aluminum is able to pour out of the vent holes. We plug the holes if they start to leak too much.
We wait as patiently as possible, and then we cut the straps, pry off the sheetrock, and get the first glimpse of the cast panel.
The discoloration is from the chemicals in the sheetrock that come in contact with the molten aluminum. It’s only on the surface and will mostly come off when we grind off any rough edges. The indents are from bubbles of air that get trapped in the mold.
Next we clean the clay out of the molds. It’s easiest to use a power washer, but it’s also fun to use a hammer.
Some of the cracks cast perfectly, and some will require a little bit of cleaning up with the plasma cutter.