Welcome to the Glass Age

31 skills probably used this approach to make the posts which supported the complex coloured glass cages around luxurious ‘ diatreta ’ vases. Appropriately, ancient writers equated the glassblower’s breath with the wisdom of the philosopher Seneca. Dating the different steps in the development of production processes is often by association. For example, glass vessels were used as burial urns and contained items needed in the after-life such as dated coins or personal memorabilia. It is now 100 years since the opening of King Tutankhamun’s Tomb in Egypt. He reigned for a short period around 1330 BC, and glass items were discovered in his tomb. A millennium ago, elaborate goblets celebrated dynasties, while decorated mosque lamps spoke of a patron’s generosity. From the time of discovery until the 19 th century, glass blown containers went through many changes. Color, for example, was introduced for artistic effect, to identify ownership and warn of dangerous content (blue medicine bottles). Another key change has been the method of sealing. Hand-blown glass has to be attached to a ‘blowing iron’ until almost the end of the shaping process; the neck is formed as a final step and requires re-heating. Creating an accurately and repeatably shaped ‘finish’ is difficult and impinges on the quality of the final seal; a poor seal means diminished ‘shelf life’. Of course, historically the introduction of corks went part way to solving this. But it was not until machine forming came along towards the end of the 19 th century and beginning of the 20 th century that screw top seals could be used. Such considerations were vital in the development of glass containers for perishable foods. Indeed, the screw top ‘Kilner’ jar underpinned the preservation over winter of fruit in jams and in syrups at a time when sugar taxes were being abolished in the UK, making the process economic. The modern glass container industry has machines creating hundreds of bottles a minute from a single furnace, with an accurately profiled shape, excellent resistance to attack and 100% recyclable. It remains a major force in the marketplace with global sales near US$ 53 billion, split between beverages, cosmetics, food, pharmaceuticals and others. Beverage packaging is dominant and wine bottles are two thirds of this total. Market expansion is driven by exports and continued demand for packaging made of glass. A vital attribute of glass is the capacity for designing unique profiles identifying a brand. Other factors are transparency and chemical inertness, ensuring long-term preservation of taste and visual impact. Weight Figure 2.3. A glass container with a seller’s seal for identification (17 th /18 th century). Source: Turner Museum of Glass.