Cardboard, ProntoPack

Words of Paperboard:
Paperboard’s Thickness

Thickness is one of paperboard’s measurable features, that sets and from which derive grammage, ridigity and weight.

How is thickness measured?

Thickness is the distance, expressed in microns (μm), measured in a given sector between two parallel probes of a thickness gauge.

Thickness, such as grammage, is useful to draw a distinction between paper, paperboard and cardboard:

  • a sheet of office paper, thinking of printer sheets, is estimated to be on average 0.1 mm thick, equal to 100 μm, but can reach up to 350 μm;
  • a sheet of paperboard varies its thickness, usually starting from 350 μm to reach up to 705 μm;
  • cardboard, on the other hand, has an average thickness that varies, especially if we talk about corrugated sheetboard, but we can state that on average it reaches a thickness of 5 mm, equal to 5.000 μm.

For the same type of cardboard and in presence of a constant density the thickness increases as the grammage grows.

The fibers obtained with a mechanical treatment generally determine an higher thickness than those achieved by chemical treatment. As well the multilayer formation allows to reach a greater thickness than a single- layer formation.

Higher thickness means greater rigidity and also higher weight, but, as for the grammage, it is possible to get a lower thickness and grammage that grants the same performance as a thicker and heavier paperboard. To be able to check the features and lighten your footprint, do not forget that you can always compare products through our free BeLIGHT tool!

The myth of the 7 maximum folds per sheet

As the thickness increases, the ridigity grows. By folding a sheet on itself its thickness increases and, accordingly, its rigidity, causing each additional fold to be increasingly hard to perform.

To challenge this simple physical law have been many scholars (and not), indeed you will certainly have heard that for a standard A4 sheet of office paper there are 7 maximum folds that can be performed.

On this issue there is much more to say: the number is not always fixed at 7, there are those who claim they are 8 (or a few more) and fascinating scenarios open up. A bit of math will be needed to study the phenomenon, but the ending will surprise you!

In fact, starting from the hypothesis that our sheet of paper is 0.1 mm thick, which is the average thickness of a printer sheet, by folding it once we will obtain a thickness of 0.2 mm. By folding it twice, the thickness will increase to 0.4 mm, and so on. For each fold the thickness of the folded sheet doubles the previous one, also increasing the required force to bend it.

With 7 folds we will have 128 paper layers and a thickness of almost 13 mm. In addition, the force to fold it would be very high and the sheet will probably break.

The protagonists of the science television program MythBusters wanted to dedicate an episode of the broadcast to challenge the myth of the 7 folds per sheet, starting from a piece of paper as wide as the surface of a football field, and have reached 11 folds! They also had to use tools certainly not equal to human strength!! If you want to have a look at their achievement it’s all recorded in this video!

Are more than 11 folds impossible?

An ambitious student came to 12 folds with an even wider sheet, but for higher figures we have to switch to theory.

Let’s suppose we have the strength to continue to fold our sheet without breaking it: the surface of the sheet will decrease every time and at folding number 23 we will have a thickness of one kilometer!

After 30 folds we will touch space because our sheet will have reached a thickness of 100 km, which figures out the shared border between Earth and Space set by the International Astronautical Federation.

After 50 folds we can even touch the sun!

But theoretically can we fold the sheet endlessly?

We would love to, but probably the answer is no.

Proceeding with the fold, after 81 we will reach the remarkable result of 127,786 light years, roughly the thickness of the Andromeda galaxy.

By the way, do not think to cross the line: our journey will probably stop once we reach 103 folds, when we will be almost outside the limits of the visible universe, estimated to be 93 billion light years.

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