Castings

The very first cast got taken out of the mold only on Monday. I did not really have any choice but to wait; I had to get the right materials for the harness at the Saturday market and wait for assistance with flipping the molds when the staff came to work after the weekend. The technology I came up with at the end of last week worked as expected. The de-molding has to happen in two steps: Step one is flipping the cast with the mold still on onto a board (needs lots of foam to pad the dome from the inside in order to prevent collapsing) and lifting the mold away. Drying does not improve the strength of this clay, in fact, makes it even more susceptible to cracks. Unfortunately, an umbrella is not really a half-sphere but a dome that stands on 8 points. One of them gave in to the stress and went cracking along when the cast landed on the board. By the minute the crack grew, opening up a sizable gap along one of the ribs. The cast was relatively clean but the edges still needed attending and with each touch the gash got visibly larger. In step two, the cast was strapped down to the board with 4 strips of fabric and flipped upside down, hanging in this harness-like structure. Two of us lowered it into a pre-prepared sandpit on the kilnshelf and two people cut the straps to get the board off. It worked like a charm. Only that the crack did not hold up (I no longer expected it...) and went straight for the opposite end, splitting the form into two equal halves. It was a huge disappointment! I expected that I would not get away with it (the first casts from any mold are usually not very good), but I still hoped that my luck would hold.
The other residents who helped me with the flipping walked away quietly and tactfully, and I felt as broken as the cast was. For only a few minutes though...
Then, I cleaned up, recycled the clay (it's better for this to happen now than in the firing!), rearranged the space to make room for casting again next day and walked out of the studio.
On Tuesday, I cast both molds. The process is unbelievably exhausting; remixing of 75L of slip, pushing barrels up and down in my studio, moving them with the forklifts took the entire day. This time, I wanted to try casting into the one-piece mold differently: a thin shell was cast first then the ribs got reinforced with gauze, then more slip was brushed on and burnished flat and even. That same night we repeated the flipping process with the harness, and this time it worked flawlessly. No cracks, no damage, the form came out pristine and beautiful.
Removing the cast from the other mold (The Awesome) required a bit of thinking, and trial and error, which took up most of the day on Wednesday. The bottom of the mold was unbolted and dropped down, exposing the bare bum of the cast. Then, a lift was set up with a columnar structure built of bricks, which was narrow enough to fit through the opening but still large enough to support the bottom of the piece. Using that to levitate the piece out of the mold, the rest of the mold was dropped down too. It kind of looked like a flower emerging. Pretty cool!
The only thing left to do is to put my hands under the form and gently cradling move it to the sandbed on the kilnshelf. Surprisingly, it worked. Now, both casts are resting a slowly drying under a plastinc tent.
Of course many things can still happen during the drying and, especially, during the firing. But the first challenges are considered to be solved.
My color tests came out amazing. Thin lines of color on smooth vitrified china. I'm in love.