Catalogue of Luminaires 57

glass causes problems in wall thickness, too little glass leads to problems in the stability of the glass
product. Square or asymmetrical shapes require very special precision when the glass is
withdrawn.Once removed, the glass post is blocked again in a much larger wet shaping block,
evened out and accordingly »adjusted« to its final shape. This is the moment where skilful
craftsmanship and highest concentration are required as this process has to be completed in just a
few seconds.
The hot, still workable glass is set in an iron mould which is closed and bolted by the mould
operating assistant. At the same time, by pressure of breath or pneumatic air, the glassmaker
blows the glass. When the glass touches the walls of the cast iron mould, it cools down very
quickly to about 600 °C and solidifies. The mould is unbolted and the glass removed still fused to
the blowing iron.
To separate the glass from the blowing iron, a few drops of water are trickled onto the link where
glass and metal meet using a wooden stick. The water hisses where the drops fall and chills the
hot glass. Small cracks suddenly appear on the glass surface. They are sufficient to separate
the glass precisely in this area from the blowing iron with one slight knock.
This concludes the manufacturing and forming process of the raw glass.
9