Tuesday, April 17, 2012

Resin, silicon and mould making


My Silicone mould

About a month ago I went and worked with the fabulous Pip from 'it was me' designs to learn all about resin casting. 'It was me' is a small Sydney based accessories label that specialises in funky hand made resin jewellery - think chunky bangles, cute earrings and creative necklaces all handmade with love. I had a great time and learnt stacks about this highly versatile material. I leant a hand with the mould making and casting of her new collection and I was lucky enough to be able to create my own mould that I will soon be using to embed some of my coral pieces in.

My mould station
I thought I would show you the steps I used to make my mould as it was quit the process for a novice like me. The silicone (and the resin I use) come from Barnes.

I was trying to create a shallow box mould and decided to mould around one of Pip's perspex boxes that she uses for jewellery display (which just happened to be the perfect size that I needed). However I needed to cast over the top of the mould so I had to devise a way to only make a mould around the top 1/3 of the box. With the help of my very handy Father I cut a hole in a piece of MDF so it would perfectly fit over the perspex box. I then propped this up on magazines to get the level I wanted and sealed the edge of the box with plasticine to ensure it was airtight (this will stop the silicone dribbling all down the sides and all over the place). I had now made a platform to mould over.

Building up the walls of the mould

Next step was to build up some walls around the box with more pieces of MDF (the MDF has a coating on it to stop the silicone from sticking to it). All the edges are sealed with more plasticine. I left about a 1.5cm gap around the perspex box.

The silicone is a two part mix, one part of a very dark pink goo and one part of a white goo. Once mixed they become a lighter pink goo. It is really important to mix the two components really well or you will get areas that don't set properly (I found this out the hard way). Time is of the essence here, the silicone begins to set pretty quickly.

I mixed it up in small parts (a cup at a time) and just kept pouring it into the mould, first around the sides then over the top until it was about 1cm thick over the top of the box. I used about 750ml of silicone for the mould.
Silicone in the mould


Notice that my mix isn't completely even and you can see unevenness in the pink silicone colour. I needed to mix the silicone a bit better to get an even consistency. For me this unevenness resulted in a few small areas that have not set and this has affected my final mould surface, there are a few little pock mark like parts on the surface. But it's not to bad so I don't really mind.


Leave the silicone to set (about 20 mins)

I then removed the mould walls one at a time and gently lifted the silicone off the perspex box.

Removing the mould walls
So now I have a lovely silicone mould that I can use again and again to cast resin.

I plan to use this mould with my smaller coral circle pieces so that the piece is suspended in the middle of the resin like it is floating in space. This resin object will become a freestanding sculpture and an alternative to my framed work.

I have experimented with embedding small pieces in reusable moulds to get me familiar with the resin casting process. So far I am pretty happy with the results. Tomorrow I try with the larger mould!

Small resin pieces

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