Float Glass

Float glass is more commonly known as window glass. Because it is inexpensive and sometimes free, it is a popular glass to use in glass fusing. There is a rainbow pallet of compatible frit and powders to use for decorating and embellishing float glass.

Please note: All float or window glass may not have the same COE. There are different manufacturers who make this glass, and they are not concerned with the COE. It is normally around a COE of 82. You will need to experiment with your glass to be sure it is compatible, or just use the same piece of glass for your work. If you get a sheet from one source and a second sheet from another source, there is no guarantee those glasses will be compatible.

There is not even a guarantee that window glass made from the same manufacturer will have the same compatibility. If you are making a large item, or want to use a lot of window glass, purchase it in large quantities so that it will come from the same production run.

Some people ask their local glass shops, or window installers for their discarded glass. This will definitely save you money.

Window glass is made by melting sand, limestone, soda ash, dolomite, iron oxide and salt cake. This molten glass is then fed through a delivery canal into the float bath or tin bath. This method of making the glass gives it a even depth and a flat surface. Because of this process, some tin is absorbed into the glass. This can cause an invisible haze on one side of the glass.

When using float glass, this haze may affect the applied colored glass. To eliminate this problem do a test firing on your glass. Fire two pieces of glass from the same sheet. Cut two pieces, and flip one side upside down. Now fire these pieces. Keep track of which side of the glass has a haze. The tinned side can also be determined by using an ultraviolet light.

A short wave UV flashlight, or a UV-C Light pocket purifier is a good way to determine the tin side of the glass. Prolonged exposure can harm your eyes, so don't use this product any longer than necessary. These flashlights or pocket purifiers can be found on line, and vary in price. Use the correct wavelength, which is short wave or germicidal. Turning down the room light will help when testing with this light. There will be a fuzzy white glow when the UV light is on the tin side of the glass, and a purplish shine on the air side of the glass.

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