Wirkkala carved the prototype of the mold by hand from a solid block of wood.
Carbonization: When molten glass at over 1000 °C was blown into the wooden mold, the heat gradually carbonized the inner surface. This reaction of fire and wood left an irregular texture in the glass that mimicked melting ice or plant bark.
2. Transfer to the Graphite or Metal Mold
The artisans of Iittala transferred the unique texture of the burned wood prototype to durable precision graphite or metal molds through pouring.
In blowing into these metal/graphite molds, the artisans maintained manual control over the temperatures and the glass mass.
Constant Roughness Effect: The texture of the mold refracted light differently on each surface, ensuring that an industrially manufactured object retained the feel and appearance of a unique hand-sculpted piece.