Cast Glass

Culture & Context

Lost wax techniques date to over 6,000years ago, the precise origins of the technique is unknown. It is more well known as a technique for casting metal but has been adapted and used to create complex glass forms since Roman times.

These examples in glass were created using the lost wax method and are parts for a larger series of sculptures. They were inspired by the collections of Mollusca related to naturalist Annie Massy, which are held at the Natural History Museum of Ireland. I wanted to recreate the sensation of peering into rock pools. As such I wanted to produce a number of pieces and lost wax allowed me to create multiple forms (snails) to be added to my larger blown glass rock pools. By using recycled glass from the blowing studio, my cast pieces were compatible with the blown works and could then be joined together hot.

Process & Production

The first step is to create a silicon mould from which multiple wax forms can be produced. This is made by pouring liquid silicon around the positive form. The silicon is cut to enable the original form to be removed. The silicon mould can be cased in plaster to give it more structure, this is usually a two part mould. Once the mould is ready, wax is melted and poured into the mould. In this way multiple wax forms can be produced.

These wax positives can then be invested in a refractory mould. When creating the mould venting is important to allow air to escape and allow the glass to flow into all areas of the mould. A reservoir can be added at this stage and this is where the chunks of cold glass will be placed for them to be heated and flow into the plaster form.

Once the investment mould is dry the wax needs to be removed, this is normally achieved by steaming out the wax, or melting it out in a hot kiln. The mould needs to be dried thoroughly before the firing process.

The correct amount of glass is calculated using the volume of the form. This glass is then added to the reservoir. The firing programme is set and the glass is heated to approx. 900 degrees Celsius and slowly cooled again.

After firing the plaster mould is destroyed in order to remove the form. It can then be cleaned and if there is extra glass in the reservoir this can be removed in the cold working studio with a diamond saw.

Recipe Details

Plaster mould = plaster silica in 1:1 ratio

Glass form = recycled glass from glassblowing production (soda lime glass)