Lost-wax kiln cast Gaffer 45% lead crystal
Every piece is individual and original, with master moulds used only for obtaining very basic wax shapes that are then built onto and/or carved back.
Each petal or part of a leaf is an individual shape cut from wax, built-up, carved, shaped and moulded by hand before being joined onto the main body or work. Usually all the components are made before assembling together to create a single complex wax to be cast.
Most pieces have many sprues added to the wax before moulding, to allow the glass to flow into difficult areas and also to strengthen delicate pieces through the kiln firing, divesting and finishing processes.
The moulding-up process into the refractory investment usually calls for a unique approach to be developed for each piece, but basically follows the NZ method of layering mould material with variations of techniques and materials to retain and protect delicate parts of the glass when breaking out of the mould after firing.
All of the wax is steamed out of the mould (Lost-wax) creating a cavity in the refractory mould for the glass to flow into. Any remaining wax would create soot marks if left to burn out in the kiln Glass is packed or placed to create colour variation and the piece is then kiln fired for about 5- 7 days.
Kiln firing time and temperature varies depending on mould curing, the thickness the glass has to flow into, trapment of air bubbles, and the annealing rate (cooling and strengthening) of the glass - again dependent on the thickness. ‘Divesting/demoulding’ or ‘breaking’ the glass out of the fired mould material takes
longer with the very delicate pieces as pressure from any tool in the wrong place will create breaks. Toothpicks are often used when getting close to the glass.
Finishing starts with grinding with diamond burrs and water; coldworking out any extra air trapped during moulding that filled with glass, and re-forming or shaping.
Sprues are cut off and surfaces ground and sanded. Specific tools are created to address individual issues or problem areas with each piece. Delicate pieces are sanded from 100 to 400 grit then sandblasted and then acid etched, some selected parts are then re-sanded to a polish finish.