26. 8. 2020
Ever wonder just how Preciosa’s master glassblowers create our amazing lighting? Read on as we share what happens every day in our glassworks.
First things first, we’ve got to make some glass. Glass production begins by preparing a glass batch (a mixture of raw materials from which molten glass is melted) - glass sand, sodium, potash and calcite. We source our sand from nearby regions (one of the reasons Bohemian crystal is so special). If required, we can also create coloured glass. Metallic oxides are used to colour the glass to a chosen shade. The glass is melted in our furnaces at a temperatures between 1430 - 1450 °C.
Fun fact: Every glassworks has their own recipe for a glass batch which is a well-kept secret - at Preciosa only three people know the recipe.
A gaffer is a master glassblower. We have about 20 glassblowers, and the hierarchy among them has been passed down for centuries. Gaffers work with a blowpipe (used to blow glass) on a bench above and their assistants are below, passing them tools, holding the mould, and taking the glass to a lehr (cooling belt). Everyone knows their place and job which creates a harmonious flow of people and glass.
The glassblowers don’t own their own blowpipe; it’s shared amongst the group. The mouthpiece is plated with gold or silver for hygienic reasons. Our artisans who create the arm pieces of a chandelier are super specialists. Their craft differs considerably from blowing. It is specifically taught and masters practice it their entire professional life.
Fun fact: The creation of a glassblower’s pipe is attributed to the Phoenicians around 300 B.C.
At Preciosa we most often use two types of moulds: wooden and metal. We have about 7000 wooden moulds and they typically can be used between 60-80 blows. Metal moulds can withstand more blows and are good for glass that requires more optics and texture. Preciosa also creates ‘temporary’ moulds made from plaster. These moulds only last for a few blows but it allows us to create custom pieces or complicated patterns that other factories might not be able to do.
Fun fact: We most often use beech wood for our moulds and it’s sourced from the surrounding forests.
We have two cooling belts which do two types of cools: fast and long. The fast cooling is suitable for smaller pieces and those less than one centimetre thick. Depending on the type of glass, it’ll spend between 1.5 and four hours cooling off from a temperature of 500°C down to 50°C. Larger pieces and those thicker than one centimetre are treated to the long cool. These usually spend the night on the cooling belt, but really large pieces can take up to a week to cool.
Want to meet a real Preciosa gaffer? Watch episode two of We are Lightkeepers and meet glassblower Vaclav.