The making of a Modern Fossil; jesmonite poured into brass shim moulds

I did some experiments creating the shapes that would be attached at each junction of the metal framework of my work for the 7 Bridges public Art project, ‘Modern Fossil‘.  By pouring jesmonite into test moulds, I could see:

• would my moulds – lengths of very thin sheet metal slotted into slits cut into foamboard – actually work?
• How securely anything embedded into the jesmonite would be
• How thick did I need to make the shapes so as not to break; it was to be mounted outdoors on a railway bridge, so needed to be durable
• What would the result be like with an acid etch on the surface on the cast shapes?

Experimenting with jesmonite with portland stone aggregate

Initial test with plastic piping

Initial test etching the surface with acid to reveal texture

Slightly illegible notes – lots of measurements!

Slightly illegible notes – lots of measurements!

Once  I was happy with the results, I had to create the metal lengths that would be embedded into the fossils (see my metalwork process done at the fab London Sculpture Workshop). I then worked out the sizes and shapes of each fossil ‘cell’ according to the junction of where it sat and made the moulds.

Glued spacers in the mould to create spaces for the bolts

Poured jesmonite, with lengths of pipe embedded

Drying in the studio

Close up where you can see the texture of the portland stone

Bolts attatched into the back of the shapes with mastic

finished pieces, ready to be bolted to the framework

Before pouring, I had to glue ‘spacers’ that would create holes in the back that I could attach bolts into. I had to work quite quickly –  pouring the mix, then sticking the tubes in – as the jesmonite sets pretty quickly. It’s one of the bonuses of using it over concrete. It is more expensive, but it’s great to work with.