There is a lot of research going on on beam-spreading in thin foils. This can be useful in many ways. Firstly, beam-spreading can be a good measure of the area of contact ratio. The higher the ratio, the more friction is likely to be present.
However, the size of the area of contact and the resulting contact load are not always the same. For example, in a thick film, a few millimeters can be covered by the film, but in a thin foil, a few centimeters could be involved.
Furthermore, a smaller thickness can be rolled up to form a thin web of metal. This is achieved through the application of horizontal tension by mandrels. In fact, in many cases, two sheets of aluminum are rolled together.
In addition to forming a thin foil, rolling is also used to make thin gage sections. Typically, these require very tight tolerances. Nevertheless, it can be a complex process.
As a result, it is difficult to obtain thin gage sections from highly alloyed aerospace alloys. Therefore, cold rolling has been developed for some alloys.
Thin foils have many unique features. They can be printed, silvered, burnished and coloured. It is also resistant to moisture and has high strength. Nonetheless, they are expensive to produce.
Thin foils are also very flexible. Unlike metal sticks, they are not fragile. To achieve the highest strength, a protective layer is often applied.
Thin foils are commonly used for backing paste jewels. In fact, jewellers have been using this material for years.