Glass-blowing is the process used to shape glass. It quite literally involves blowing with your mouth through a blowpipe at the end of which is molten glass – a combination of limestone, sand, potash and soda ash that has been heated to more than 1,000C. Today's glass-blowing courses combine traditional skills with contemporary techniques for both beginners and those with some previous experience. Students learn how to use a blowpipe to form a bubble with molten glass, shape glass with a marver and special glass-blowing tweezers, and use the punty, paddles, jacks, and shears to add to the design and shape. These skills are then used to design, produce and decorate all kinds of glass objects from scientific equipment to ornaments, tableware, mirrors and works of art. While the temptation is there to make jokes about people in glass houses, it's a deadly serious subject – the high temperatures mean there's a huge emphasis on health and safety.