First let’s look at some of the properties of tin. Tin has a low melting point, 505 K. For reference, aluminum melts at roughly 933 K and carbon steel at roughly 1800 K. This low melt point is tin’s biggest weakness compared to structural metals but it is also its more important characteristic. Liquid tin does not boil until 2900 K. It also has a very low viscosity and wets the surface of most materials.

Given the characteristics described above it makes sense that most Sn-alloys are used for solders. Tin-lead (Sn-Pb) alloys have historically been solder but more environmentally friendly options such as Sn-Ag-Cu (tin-silver-copper) alloys do exist and are becoming more widespread.

Ok, so solder and foil aren’t that interesting, I know. Remember what I said earlier about tin’s high boiling point and low viscosity? Well, the surface of molten tin is also perfectly flat. Using these properties, molten tin can be used to create large, flat sheets of glass, called “float glass”.

Imagine a continuous river of molten tin, now pour molten glass onto the tin. Tin is a good head conductor and it has a perfectly flat surface so it conducts the heat quickly and uniformly allowing for a perfectly flat piece of glass with a uniform thickness to form on the molten tin surface. Pretty cool, right?

The idea of float glass has been around for awhile but it was not successfully implemented commercially until the 1950s. Sir Alastair Pilkington, a British engineer, gets the credit for the process that is still used to produce about 90% of flat glass today. There are a few other details to the process but the basics of it are pretty simple. Thickness can range from around 0.1″ to 0.6″ so the float glass process can be used for a wide range of large, flat glass panels.

Think about it the next time you go window shopping. How were those large, flat windows manufacturing? Odds are it was using the float glass process.

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