Glassworks Know-how
Did you know that glass, or liquid sand is an amorphous solid that is neither liquid nor gas and is always moving, funny how we interact with glass everyday but never stop to think about this versatile material, well lets end our ignorance today and explore glass.
Glass, a non crystalline solid, because of its transparency and chemical inertness has found its way into various industries leading to both domestic and commercial usage, the common terms "a glass of water", "glasses" or magnifying glass" are all due to the material's influence. It was not until some 3600 years ago during the Mesopotamian era that the usage of glass started to take place, but the earliest known glass dates back 4000 years, glass was used even before that during the stone age but as volcanic glass or obsidian.There are two main methods of glass production, float glass for making sheet glass and the glassblowing that produces glass bottles and other types of containers. The primary ingredients for making glass are sand, limestone, dolomite/calcium magnesium carbonate, soda, sulfate, and cullet glass, this mixture is called the batch, the batch mixture is then heated to 1500-1600 deg celsius to melt and form the glass ribbon into float or flat glass or in the case of bottles or containers it is formed into glass gobs, the glass melt is then supercooled, liquid glass does not crystalize during the rapid cooling process due to its high viscosity, as a result it has an amorphous structure and not crystalline, its viscosity gets lowers with heat and gradually it converts from solid to liquid state, when supercooled, the glass melt goes from a liquid state to a plastic one, and if the temperature is increased, it passes back into a liquid, be it as either ribbon or gobs, and depending on requirement it is then annealed, cut or blow molded to the required size and shape, at the final stage is checked for any defects before dispatch, there are various types of glass and can be catered to fit different needs, some types of flat glass include.
➽ Flat Glass: Flat or float glass is the basic first produce from the float glass ribbon, they are mainly used on glass doors and windows, it has a uniform thickness and it acts as the base for any type of float glass products, but they break into long shards and are much suited for double glazing after further treatment.
➽ Annealed Glass: It is essentially the float glass that has gone through the annealing process or the cooling of hot glass on one side with cold blasts of air taking care of any stress giving it a more clear finish making it easier for cutting, shaping etc, it is also used on windows, doors etc and they are the base for other types of glass such as tempered, laminated etc.
➽ Tempered Glass: Tempered or toughened glass is a kind of glass which is much more stronger when compared to its predecessors, by using float or annealed glass and further heating it to 1200 degrees and its cooling rapidly it allows for the inside of the glass to cool slowly creating internal tension and external compression, making it stronger and when it breaks it shatters into smaller blunt pieces, this makes it quite suitable for automobiles, mobile screens, bathroom doors etc, it cannot be cut or drilled into making it complicated to work with.
➽ Laminated Glass: This kind of glass is made from adding two or more sheets of annealed glass together with a thin sheet of polyvinyl butyral or similar material to hold it together if it breaks, making them stronger and also safer, they are also called safety glass, these kind of glass are used in windows and doors in building that are more likely to be exposed to tornados, hurricanes or similar circumstances of breakage.
➽ Heat-Strengthened Glass: This is similar to tempered glass but additional heating and cooling is added to the glass making it much more stronger but the they are cooled slowly to reduce any tension within the glass and thus it breaks into shards incase of a breakage, they are much suitable and preferred in environments of high thermal stress.
➽ Wired Glass is an older types of glass that works the same way as a laminated glass except instead of using a transparent sheet material, wire is used to keep the broken shards in place, that way in the case of high temperatures and breakage the glass would still be held in place, these kinds of glass are mostly used in schools hospitals etc.
➽ Insulated Glass: This type of glass inhibits the transfer of heat from one environment to the other, rather than the glass itself being insulated, it is separated by a thin layer of air, vacuum or an inert gas and is held by a frame and thus keeps the heat or cold on either side of the environment, it is also called double or multiple glazed depending on the number of layers used.
➽ Mirrored Glass: Mirrored glass is mostly used for aesthetics, they reflect surfaces by the metal on one side it that has reflective capabilities such as silver or aluminum when melted and coated on one side of the surface.
➽ Borosilicate Glass: Also know as pyrex, is one of the most commonly used glass for containers since it has a low expansion coefficient, allowing it to resist breakage caused by temperature changes, and they consist of various elements that resist chemicals of strong acids and alkalis, it is made of 10% boric oxide, 80% silica and small quantities of aluminium and sodium oxide, they are used widely in pharmaceutical, chemical etc
➽ Soda Lime Glass: This kind of glass is another widely used type, they are used to make drinkware, tableware, bottles, jars etc, it is composed of silica, calcium and soda, more the percentage of silica more it resists thermal shock, they are good at resisting reactions, thus are good at storing food items, neutral aqueous and acidic chemicals etc.
➽ Lead Glass: Lead glass is known for its softness and is mostly used in decorative items, they do not withstand a lot of temperature or pressure, it is made of 54-65% silicon di-oxide, 18-38% lead oxide, 13-15% soda or potash, and various other oxides. When the content of PbO is less than 18%, it is known as crystal glass, the percentage of lead decides the types of lead glass, full lead glass is 30% or over, 52% are used for radiation protection etc.