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Test castings

Moving along in my project I realized I needed to solidify my ideas and come up with a final form for these objects to manifest themselves. Taking inspiration from my previous test of casting the foam cutouts in plaster, and my prior experiences in concrete, I decided to try casting these shapes in concrete. For my initial tests I used previous foam tests from the syringe pump calibrations which is why these casts vary so widely in thickness and form.

These first tests were done in a concrete product I am familiar with, Rapid-Set Mortar Mix. This has been a great product for me in the past producing fine details in small castings and skinning larger objects because of its short setting time and lack of large aggregate. However these qualities and it’s significantly higher price may not me ideal for larger castings so I tried experimenting with more traditional concrete products.

The first 2×2 test used some foam forms close to my final design, but again these are just samples. I used this opportunity to tests a few things at once.

First I used quickrete, a new product to me which contains sand and gravel along with the cement. This turned out interesting since sand and gravel evidently does not absorb water like the mortar does, so much less water is needed; I however, did not adjust my recipe and ended up with a very watered down soupy mess. Surprisingly it still set up, produced decent details, and supported itself when suspended. In theory concrete with too much water is weaker but it was good enough for my test.

About that suspension, I also used this test to try out some holding options. These castings will be heavy and I’ll need a way to carry and display them. Since I’m still not sure if they hang on the wall, lay on the floor, or ideally, assemble into a freestanding sculpture I need a versatile solution. The three things I tried were an imbedded cleat, protruding bolts cast into the concrete, and an imbedded coupler nut cast into the concrete and bolted through a mesh insert. This last option seems the most useful and flexible depending on how I set these up for display. After making this casting I suspended the concrete from this connection for several days without structural failure.

My last objective from this test was determining weight. The 2×2 grid weighs 30lbs (still fresh and rather wet), but this let me know about the weight of the final 4×4 panel, about 120lbs.


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