Glass manufacturing was discovered in ancient times and reached its peak in the Middle Ages, when many illustrious workshops were in operation. The initial products were created by different methods, for example pulling out the glass fibre and wrapping it around a clay core. The first people to use the blowpipe were probably the Phoenicians (cca 1500 – 300 BC).
Blowing the glass allows the glass masters to create final shapes either by free-blowing or mold-blowing.
The temperature of lightning is 20 000 C, while the melting point of glass is between 500 ° C and 1650 ° C, depending on the type of glass and its content.
Broadly speaking, there are three phases to melting glass:
- Fusing – the mixture of the ingredients is melted by increasing the temperature in the furnace. The temperature varies depending on the type of the glass.
- Purification and homogenization – two phase taking place simultaneously, in which the gas bubbles are removed from the mixture. At this point the glass melt reaches the peak temperature and the viscosity is the lowest. The temperatures at this point are usually between 1400 and 1500C.
- The last step is to decrease the temperature to appoximately 1200 C – the point at which the viscosity increases and the glass melt is suitable for casting and hot forming.
View into the furnace during the glass melting phase
Blowpipes in the work station
Blowpipes, scissors, and tweezers are the necessary tools of a glass master
The base of each glass product is a flask, which is blown by a glasspipe
Free-blowing – using several tools to help to achieve the desired shape
Cooling the blowpipe during the process of forming
Cooling the mold after use
Final product with the cap which later will be cracked off by creating the shock temperature difference.
The final products are going through the cooling furnace at a temperature of around 600C. This is to ensure the controlled cooling of glass products and to remove the internal stresses in the material.
Final inspection and packing of the products
Photos: Dana xbone Hosova