Silicone casting 15/01/19

river project, UNIT 2, Videos, Work in Progress

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I decided to make silicone casts of the bones, to explore a different material and its potential for my project- and luckily someone else in the foundry also wanted to work with silicone too, so Lindsay mixed up the last bit of silicone she had for us both to use. Unfortunately there wasn’t enough to cast the brick or jaw pieces, so I may revisit this material once she has more in stock. The photos above show the process- weighing and mixing the two parts of the silicone, then pouring it into my moulds, the same as when I used the wax and plaster, as well as photos of the silicone bones de-moulded.

The above video shows clips of all the bones, and demonstrates the qualities of the silicone- as you can see it is a very tactile material that I have had a lot of fun playing with! There is something very surreal about squashing a pink bone in your hands, and being able to fold it then watch it spring back when you let go, and I am very happy with the results of this experiment.

When I get the chance to present these to the class the main feedback I want is whether or not to cut off the excess silicone- the bronze and aluminium casts don’t have the “feet”, but the plaster and glass wax pieces do, so this is something I need to consider when deciding what to present and how in the final exhibition.

Removing Excess Metal from the Casts

river project, Videos, Work in Progress

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The photos above show the process and tools used for this stage of the project. As you can see I used a clamp to keep the casts in place whilst cutting and grinding off excess metal using a Dremel and angle grinder. I had to remove the cup, and all of the runners, risers and wax channels as they had all been cast in metal. This was hard work as the studio has been reaching 35 degrees Celsius, so I had to take frequent breaks and stay hydrated. On a few occasions the technicians closed the workshop completely as it was too hot to work in, and on other occasions I did the work in the metal workshop rather than the foundry as it was a few degrees cooler.

As well as removing excess metal I also used the Dremel and an engraving tool to work back in details that had been lost in the casting process, such as holes in some of the bones, and textures where they had been lost.

It took a bit of practice for me to get to grips with using a Dremel and angle grinder, as I had limited experience with only a Dremel, previously. However throughout this stage I learnt very quickly how to handle both tools properly and effectively, and I am really proud of myself for it- I have always been a bit scared of electric power tools but I pushed myself and am really pleased with how far I’ve come.

Before and After Clean Up Bronzes from Kat Outten on Vimeo.

The video shows the bronzes and aluminium pieces still attached to each other by the runners and risers, and then each bronze bone once I had finished working on them. As you can hear me say in the video I’m not 100% happy with each piece; I feel that the pieces of jaw both need a bit more work to add back in lost details around the teeth, and one of the bones in particular I want to go back and work into further as I am not happy with the hole (I broke two Dremel heads trying to fix it) or with some of the texturing on one side. However due to time constraints I had to move on to the patina stage, so that I would have some finished pieces to put in the end of year show.

Unfortunately I only had time to finish the bronze bones, so both brick casts and all of the aluminium bones will have to be finished when I get back from the Summer break. I am a bit disappointed by this, but the casting process is incredibly time consuming, and I want each piece to be the best it possibly can be, so I am trying not to beat myself up over not getting everything finished.


Prepping the Moulds for the Kiln/Setting up for the Pour

river project, Videos, Work in Progress

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Before the moulds could be fired in the kiln, Becky removed the plastic from the outside (that we had used to make the moulds, as seen in previous posts, and the brick video). We then had to cover the sides and bottom of each mould with layers of scrim coated in plaster, to create a protective barrier to stop the plaster moulds falling apart in the kiln- four of us did this, and I didn’t take any photos as it was very messy! But you can see the moulds with their plaster coating in the above photos. The moulds then went into the kiln upside down, as you can see in the photos. They go in upside down so that as the mould is heated and the wax inside melts it will flow out of the mould, leaving empty spaces where the metal will then be poured.
The next step was to vacuum the insides of the moulds to ensure they were free of debris, ready for the pour. Once this had been done the moulds were ready to be winched into place using the pulley system in the foundry, and set up in the sandpit ready for the pour.

The video shows the technicians winching one of the moulds into place, I kept out of the way for this part as I hadn’t done it before and wanted to watch and make sure I knew how to do it for the next moulds. I then had to dig the moulds in, making sure the sand was packed in closely around each mould to ensure stability for the pour. To keep the moulds clear each one had a piece of wood placed over the top.

This was definitely one of the more arduous parts of the process- it took five of us to do the plaster coating, and four of us to get the moulds from the kiln into the sandpit, as each one was incredibly heavy and fragile. I was careful to follow all instructions from the technicians to make sure nothing went wrong!