1,679

by thecastingfloor

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Our pace has quickened here on the casting floor. We are working long days to get ready for production casting. Sleep and apron care have been neglected.

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Here is the reason for the hurry. We figured out how many tiles we need to make by the end of March. You can see the numbers here, broken down by shape and color. Written in green at the bottom is the number that keeps us up at night: 1,679. Including a 20% cushion, that’s the total number of finished tiles we need by the end of the residency. Working backwards from then it means, more or less, that we need to cast 21 molds twice a day for 50 days. 50 days starting Friday. Hence the rush.

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We will be ready, though. We finally found a surface we like for the south-facing side of the wall, the part of the installation that will be part of the passive solar design of the house. The original vision was to make pieces that looked like they were carved out of slate and we actually got pretty close to that.

There are lots of smart people at Kohler, ceramic engineers and glaze analysts, that have helped us get to this point (a special thanks to Mike Carson!). We tried a lot of different things, but in the end we decided to simply add stain to the Kohler slip, which produces a great color. The Kohler clay formula fires so tight and vitreous that we can get away with not glazing. It comes out of the kiln a little toothy, though, so we will be wet sanding each piece. We figure we can afford to spend two or three minutes on each tile, and we loved the surface we could get in that time, which is smooth and satiny. We are fielding suggestions on how to eliminate the sanding, though, maybe through fine-media tumbling or blasting. Please let us know if you have any ideas.

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To color the tiles without using thousands of dollars worth of ceramic stain, we mix the stain with a small batch of slip and paint that onto the open face of the mold. Then we close up the mold, insert the funnels, and fill the whole thing up with the regular Kohler slip. Wait three hours, empty the funnels, and we end up with a solid tile that has a layer of color on all the visible faces.

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Originally we thought we would make a number of models for each shape. Otherwise, any imperfection in our model would be repeated in every instance of that particular shape. That seemed to betray the process in a way that felt unprofessional. The fact is, though, that we’ve gotten to know these shapes so well and have gotten so good at making the models that they are essentially flawless. Like for instance this beauty that Daniel finished yesterday.

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So, we can get away with making all of our molds from one positive without worrying about repeating some visible flaw. That led to another challenge, though, which is that making molds is actually pretty hard on a plaster model. We are making up to eight molds for one shape, and the plaster model would simply deteriorate too much before we got to the eighth.

Instead, we made one mold from our plaster model, then cast into that mold a new positive in Densite, which is a weird material made of both plaster and cement. It doesn’t look very clean in the picture, but the lines and faces of our Densite positives are a beautiful sight. And it took repeatedly slamming a piece against the corner of the table to break it. So on Friday, with our new Densite models, we entered a mold-making fugue state.

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Here are twelve of our twenty-one molds that we need by Friday. I can’t remember anything about this past weekend, but we came in on Monday and apparently we’d made these.

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And just because I didn’t want to leave you with a boring picture of molds on a cart, here’s a cool mural from another building at the factory. It reads, “He who toils here hath set his mark.” Doesn’t really roll off the tongue, and I’m sure they mean “he or she,” but there you have it. We have certainly been toiling.

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