Infinite Sets. If you continue to study this subject you will find discussions about infinite sets, and the idea of different sizes of infinity. That subject has special names like Aleph-null (how many Natural Numbers), Aleph-one and so on, which are used to measure the sizes of sets.
For decades, glossy paper, the type used in magazines, was made using a white clay called kaolin (named after the Chinese region Kao-Ling where it was mined to produce porcelain).
Paper roll for thermal fax machine. Thermal paper is a special fine paper that is coated with a chemical that changes color when exposed to heat. It is used in thermal printers and particularly in inexpensive or lightweight devices such as adding machines, cash registers, and credit card terminals. The surface of the paper is coated with a solid-state mixture of a dye and a suitable matrix; a combination of a fluoran leuco dye as an example.