The history of float glass and the main differences with tempered glass and extra-clear glass

Jan 17, 2023

From the manufacture of tables and small tables, through mirrors and windows, to doors and household electrical appliances: float glass is the most common type used in the manufacture of products in which glass is one of the raw materials.

After an initial introduction to the origin of float glass, we will analyse its:

  • Characteristics and advantages;
  • Differences from extra-clear type;
  • Differences from tempered glass.


The history of float glass

It was in 1952 when Sir Alastair Pilkington completed the development of the manufacturing process to obtain float or floating glass.

This peculiarity of floating glass comes exactly from one step in the manufacturing process, that in which the sheet is floating on molten tin.
While in the beginning the maximum thickness obtainable was 6 mm, today it is possible to guarantee customers thicknesses between 0.4 mm and 25 mm.

The production process of floating glass

After appropriate mixing, the raw materials required for the production of float glass are moved to the melting tank and enriched with cullet.
At this point, the glass mass arrives in the tin bath in a controlled atmosphere: the glass, floating on the tin, is distributed to make the sheet.

Depending on the speed of extraction from the tin bath, it is possible to work on the thicknesses that can be obtained: the faster the sheet is extracted, the thinner the thickness.

The finished glass, transparent and with parallel surfaces, is the result of a controlled cooling process.

Float glass and extra-clear glass in comparison

In the furniture and appliance industry, float glass is also used in the more sophisticated extra-clear, colourless and totally transparent version.
The traditional float glass version, on the other hand, has a greenish nuance due to the presence of iron oxide.

To obtain the extra-clear variant, the iron oxide is almost completely removed; in addition, there is a specific type of crystalline silica that is lighter than the one commonly used.
In addition to the differences in appearance, the extra-clear glass has a higher quality than the float version.

The clear shade makes it more pleasing to the eye, brighter and more suitable for highlighting objects placed on it.


A comparison with tempered glass

Float glass and tempered glass differ due to their respective production processes. Compared to the process just described, thermal tempering (this is the name given to the processing performed to obtain tempered glass) involves:

  • Very high temperatures (we are talking about over 600 degrees);
  • Rapid cooling by air jets.

The end result is a glass that is elastic, strong and incredibly resistant compared to the non-tempered variant.

The limits of floating glass

The above considerations lead us to identify what are effectively the limitations of floating glass that make it unsuitable for certain uses:

  • Low level of safety;
  • Low mechanical resistance;


The floating glass proposed by TF VETRITALIA

For the household appliances industry and for the production of glass for stoves and ovens, our company offers different glass proposals: coloured glass, coated, decorated and with laser markings.

The heat treatment and screen-printing process allow us to obtain a final product that is aesthetically pleasing but, above all, characterised by considerable mechanical resistance.