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Written by Josephine Lityo, Design & Edit by Celine Lityo
! Today you will learn all about glass, including the famous glassblowing technique. Glass is a mixture of melted silica dioxide, modifiers (single charged atoms; potassium and calcium), and intermediates (chemicals that act as network formers and balance it; aluminum and zinc).
This mixture is essentially where a bunch of constituent (a substance that is made up of 2 or more substances mixed together in unfixed proportions) atoms are heated up to form a rigid line net wall, where every silica atom is linked to 4 oxygen and other silica atoms, with sodium and calcium atoms in between the holes.
‌ Humans have been making glass for approximately 5000 years, which allows us enough time to improve glassmaking techniques as well as explore a variety of glass types. Silica Dioxide, is present in the form of sand and soda ash from hardwood forests, available for most cultures to access. Glassmaking is believed to be discovered around 3500 years ago in Ancient Egypt and Mesopotamia. Although, the specific origin of glassmaking is unknown, 2 theories have been ruled out as the most likely. The first theory claims that Egyptians discovered glassmaking when Written by Josephine Lityo, Design & Edit by Celine Lityo
lightning strikes the desert sand which forms a hard and moldable rock like substance. The second theory is, after Phoenician sailors were done cooking their meals with fire on the beach, they found that the sand beneath their cooking pots transformed into some liquid that cooled down into glass. However, the second theory is less likely since, cooking fires aren’t able to reach the temperature required for glassmaking. Glass could also be the substance left in the bottom of ceramic and metal working pots.
Silicon dioxide found in sand is first heated to an extremely high temperature of 1700°C. When the glass finally cools its entire molecular structure changes, the glass is no longer considered as a solid but an amorphous solid (between a solid and liquid, but the crystalline order from the solid to stop the random movements of the random movements from the liquid molecules). Soda lime silica glass is the most common glass around us. This type of glass is easiest and cheapest to produce and work with and has with relatively good chemical stabilization and quality. The glass is composed of silica (silicon dioxide) (70%), soda (sodium oxide) (15%), lime (calcium oxide) (9%), and other compounds (magnesium oxide and aluminum oxide) (6%). After the silica is heated, soda is added to lower the transition temperature which increases the water solubility, so calcium oxide, magnesium oxide, and aluminum oxide is added to bring back the chemical durability and decrease the water solubility.
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Glass was considered as a luxury for a long time as it was made in small quantities. As time moved on, different types of metallic oxides or sodas were added in order to create different colors. Color Royal blue Turquoise blue Green Amber Opal Aquamarine green Red Brown and antimony yellow Ruby
Colorant materials Cobalt oxide Copper oxide Chromium and iron Iron, Sulphur, and carbon Fluorine Cupric oxide Cuprous oxide Iron A little bit of copper and gold
Written by Josephine Lityo, Design & Edit by Celine Lityo
Glassblowing enables glassmakers to create large pieces of glass.
It starts with the gaffer or glassblower reaching into the furnace to grab the molten glass with a steel blowpipe.
The gaffer then puts the molten glass on a steel table and rolls it to get a cylindrical shape. The gaffer then puts it back to the furnace and blows through the blowpipe while spinning it in a constant motion.
The next step is optional, the molten glass is given designs and colors while the gaffer turns the pipe to keep the shape. The gaffer then sits and rests the pipe on steel arms and turns it with one hand and uses a variety of tools (stainless steel tools, cherry wood blocks, wet pieces of paper, wooden panels, etc.) to create the desired shape. This step is repeated until the gaffer is pleased with the final product.
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Then gaffer will then put the molten glass back into the furnace and tries to wrap it to break it off the pipe, this step could also start the process all over again if the glass can’t be broken off. Afterwards they will use a variety of tools to create the opening of the desired container, when satisfied the gaffer will take a punty (a metal rod) and hit the glass firmly to make it drop to a box thickly filled with layers of fire blanket. The final step is to put the glass piece to an annealing oven where its kept at about 515°C slowly transitioning to room temperature for 14 hours to prevent cracking or breaking.
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Written by Josephine Lityo, Design & Edit by Celine Lityo