Nathan Gallardo

Sound Design || Music || Audio DIY || Game Dev

Experimenting with Dental Alginate and Plaster [Prelude to Silicone Ears]

In preparation for my Binaural Dummy Head Microphone project, in which I’ll create silicone replicas of the human ear, I decided a trial run would be a good idea to try and avoid any unforeseen mishaps when it came to the real thing.

There are 4 steps to creating the silicone ears:

1) Create a mould from the human model using alginate.

2) Create a positive cast using fine casting plaster.

3) Create a silicone mould from the plaster cast.

4) Create the final silicone positive from the silicone mould.

The first two steps are vital because silicone can not be applied directly to the skin. Alginate is a non-toxic moulding agent that is perfectly safe, in fact dentists use it to take dental impressions. I found the best price for alginate was on eBay, and I bought the plaster from the 4D Model Shop in east London.

So here’s my trial run of steps 1 and 2, using my finger as a model.

I made a tube out of cardboard covered in cling-film big enough that my finger wouldn’t touch the sides. I mixed up the alginate according to the instructions: 1 part alginate to 1 part water. It sets completely in less than 3 minutes so you have to work really quickly. The alginate went into the tube, followed by my finger.

I don’t have a photo of this, use your imagination.

A couple of minutes later I wiggled it free. Alginate breaks down quickly so I mixed up the plaster of paris immediately: 2 parts plaster to 1 part water. Pour that into the mould, above the level of the alginate so you have a base.

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I left it for a couple of hours then carefully removed the cardboard.

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Use a razor to cut into the alginate and start peeling it away. It comes away quite easily, so be gentle to protect the cast inside.

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The cast came out pink….

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…But faded to white overnight.

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It’s incredibly detailed, every single wrinkle, line and even my fingerprint is reproduced perfectly. It’s really, really easy to do. Next stage: silicone moulding and casting.

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