Glass wares are made by glass blowing technique by shaping glass into different forms. Glass blowing could be of two types – off-hands blowing and lamp blowing. Glass blowers are people who make glass articles manually. Let’s see how glass wares are made by off-hands blowing.
Glass is heated to its molten state inside a furnace or oven at a temperature of 2025 – 2125 degree Fahrenheit. A glass blower uses a blow pipe, which is a hollow steel tube. One end of the blow pipe has got the molten glass and the other end is in the hands of the blower. The basic principle of glass making involves inflating the molten glass with the help of a blow pipe and working into any desired shape.
When the steel tube is rotated continuously in the furnace, molten glass is gathered at one end of the tube. It is now rotated over a flat table made of thick sheet of steel. This table is called marver. When the molten glass is rolled over the marver, it absorbs much of the heat. The glass gradually hardens as it cools down. If the bottom or sides get too thick, the molten glass is re-introduced into the furnace and then rolled again.
The glass blower then blows air into the blow pipe. Heat causes the trapped air to expand inside the molten glass introducing an air bubble into it. This bubble acts as an elastic skin on the interior of glass. Thus by inflating, the molten glass can be worked into desired shape.
While making a bigger piece, in order to gather more glass around the bubble, it is inflated and then rolled over the furnace again. After this, marvering the molten glass over the table helps move the bubble to the sides or bottom depending on the desired shape. Shaping is done with the help of tools called jacks. Once the piece is done, it is placed into a bucket of water with the other end of the blow pipe closed. The piece could then be removed from the blow pipe with the help of a wooden block.
Instead of using one’s own skills to shape the glass, it could also be inflated into a wooden or metal carved mold. Glass eventually takes the design of the mold. With the same principle, modern automated glass blowing techniques produces glass wares but without much human intervention.