Glass Making

Glass making has been around since before 2500 B.C. At first, it was considered an art and very few could do it well. That made glass very valuable, and those who could engage in glass making very sought-after professionals.

Today, glass is common, and the process of glass making is now an industry.

Silica sand, also called quartz sand, is the primary ingredient in glass making. Sand without any iron impurities is sought after for making clear glass. The iron content in the sand would give any glass a greenish tint.

Once the silica sand is available, the next step in glass making is to heat the sand to 3090 degrees Fahrenheit. This incredible temperature literally melts the sand.

When the melted sand cools, it doesn’t return to the gritty substance you started with. Instead, it goes through a total transformation and becomes a product with a completely different internal structure. Regardless of how much the sand is cooled in glass making, it never becomes a solid.

Instead, it’s somewhere between a solid and a liquid. Scientists call it an amorphous solid.

In commercial glass making, the sand is mixed with recycled glass, soda ash, and limestone. The soda ash lowers the melting point of sand and saves energy, but this kind of glass would literally melt in water. This brings in the importance of limestone in glass making. It prevents the melting of the glass in water. Thus, the typical glass around you every day is soda-lime-silica glass.

In glass making today, the melted sand is poured into molds to make bottles and other containers. Or, if it is to be made into sheets of glass, it is floated on top of a large vat of molten tin to make the flat sheets like those used in windows.

For unique shapes in glass making, the glass makers can wrap a lump of melted sand around a long hollow tube and blow into the tube, making any unique shape they want. This kind of glass making, called glass blowing, is a skill that has to be learned and practiced.

Other kinds of glass can be made by adding other products to the molten sand. Oven proof glass is made by adding boron oxide to the mix. Lead oxide makes a glass that is easily cut. Stained glass is made by adding different metals to the melted sand.

Whatever kind of glass you have when you need repair or replacement, call FEDERAL GLASS AND MIRROR at 508-872-3563. Mike and John Purpura have a long family history of excellence in many types of glass replacement and installation.