Glass-blowing

Some of my friends have shown an interest to what is now becoming a very expensive hobby of mine, Glass Blowing. I will try to describe process of making a glass for your reading and fact-collecting pleasure.

1) Raw Materials-

• Silica
• Soda-Lime
• Lime-Rock
• For Colour - cobalt monoxide (for blue) , manganese dioxide (for light purple), copper II oxide (for light blue), sodium dichromate (for Green), sulfur (for brown), cadmium sulfide (for red)

2) Equipment-

• crucible
• kiln
• gory hole
• annealing oven
• tools like - jacks, shears, iron rods, molds, pipes, paddles, marver, calipers etc.

3) Procedure -

• the first three raw materials are compounded in a V-shaped mixing machine.
• these raw materials are melted in a crucible within a kiln at 1400 degrees C.
• the molten glass is picked up at the end of a blowing rod to the desired quantity.
• the blowpipe is kept spinning and some air is blown into it. It is gathered in a steel marver (or round bowl), so that the molten is equal and rounded into a sphere.
• air is blown into it while keeping it uniform on all sides by twirling the rod, or air is blown keeping the molten in the mold.
• the bottom of the glass is shaped. If it is a mold-blown glass, then the bottom is flattened.
• then, another pole (called ponte pole) is brought with a very small amount of molten glass, and this molten is attached to the flattened bottom, and the glass is detached from the first blowpipe.
• the detached lip/rim part is then stuck into the "gory hole" and softened by reheating as the glass is malleable only at 1000-1200 degrees C.
• this detached part is what will be the rim of the glass. it is widened by using a pair of tongs. all the while twirling the ponte pole in order to keep the glass rim round.
• the glass is then detached from the ponte pole and using a blow torch, the bottom is smoothened.
• the glass is then placed in an annealing oven set at 600 degress to cool overnight. (if cooled in the open air, the glass will cool faster and cause warping)

4) Techniques -

• bubbles are intentionally formed by adding sodium bicarbonate and rice bran(the foaming raw material) to the molten glass in the crucible.
• cracks are intentionally produced by dipping the blown glass while still molten in water momentarily, then reheated and shaped accordingly.
• coloured bits (like there are in the glasses I made) are made by slightly twirlling the blowing rod with molten glass in bits of coloured crushed glass. The molten glass is heated again in order to melt the bits of glass.

omoshiroi ne?