The notion that you can only fold a piece of paper seven times, regardless of its size, is a popular myth. In reality, the number of times you can fold a piece of paper depends on its size and thickness, as well as the method and tools used for folding. The famous "seven times" limitation comes from a simple mathematical calculation based on the exponential growth of the paper's thickness with each fold.
When you fold a piece of paper in half, its thickness doubles. For example, if the paper is initially 0.1 mm thick, after one fold, it becomes 0.2 mm thick; after two folds, it becomes 0.4 mm thick, and so on. The thickness increases exponentially with each fold.
So, after seven folds, the thickness would be 2^7 times the original thickness, which is 128 times thicker than the initial paper. This is already quite thick, and it becomes challenging to fold beyond this point due to practical limitations like the paper's stiffness and the inability to apply sufficient force to make the folds.
However, with special techniques, large enough paper, and the use of machinery, it's possible to exceed seven folds. In fact, there have been experiments using massive sheets of paper and industrial equipment that achieved more than thirteen folds.
Regarding other materials, the foldability depends on their flexibility and structural integrity. Thin and flexible materials like certain fabrics, plastic sheets, or very thin metal foils can be folded multiple times, but eventually, they would encounter limitations due to the same principles of exponential growth of thickness with each fold.
In summary, while the "seven folds" rule is not an absolute hard cap, it represents a practical limitation for most everyday situations. With specialized techniques and materials, it is possible to exceed this number, but the exponential growth in thickness makes folding exponentially more challenging with each additional fold.