Why Is Sodium Silicate Called Water Glass?
Sodium silicate is a special compound created by combining sodium oxide and silica. It comes in several forms, including powders, gels and most commonly as clear, rocky pebbles that resemble glass. Sodium silicate is nicknamed "water glass" because it's water soluble and turns into a viscous liquid when dissolved, but resembles small shards of glass when dried out.
Sodium silicate is an extremely water-soluble substance that will turn water very viscous if enough is added. However, the substance will return to its normal, solid form when it is dried out. The solid form has a glassy, angular look to it, which is why ancient alchemists nicknamed the substance "water glass." It is produced primarily by fusing sand (silica) and sodium carbonate in laboratories.
Sodium silicate is available in various forms as paste, liquids or in dry form. The viscosity of sodium silicate depends on how much water is used when mixing. For example, sodium silicate sold in liquid form is actually a solution of water and sodium silicate. Because there's far more water than sodium silicate means that it is still liquified. Sodium silicate paste, which may be used to make repairs to glass, has about 1/2 water and 1/2 sodium silicate, making it thicker and easier to handle. Dried sodium silicate resembles glass powder and is free of moisture.
A variety of different industrial uses for sodium silicate exists. It is used primarily to repair items; placed into a leaky engine while in liquid form, it plugs the leak when it dries. It may also be used to coat fire-proof paper, wood or cement. It is used for fixing pigments in paintings by applying a small coat over the work, acting as a protective shield. Sodium silicate is also used in water treatment, petroleum processing and even as a detergent.
Use in Eggs
Water glass was once used in long-term egg storage. The Reliance Ink Company of Canada was among one of the companies to sell water glass to consumers in the form of a powder that turned a container of water into a gelatinous solution. People who wanted to store their eggs for long periods of time (up to two years!) could place them in the container of water glass, which prevented oxygen and moisture from reaching the egg and inhibiting bacterial growth. The use of water glass to store eggs is not as widespread as it once was, however, since large-scale egg farming increased supply. Consequently, because of increased supply, people no longer have to keep the eggs for long periods, as a precaution against a possible shortage of eggs.