How Does Carbonless Paper Work?

Carbonless paper, also known as non-carbon copy paper or NCR paper, is a type of coated paper designed to transfer information written on the front onto sheets beneath. 

Carbonless copy paper consists of sheets of paper that are coated paper,coated with micro-encapsulation|micro-encapsulated dye or ink or a reactive clay. The back of the first sheet is coated with micro-encapsulated dye (referred to as a Coated Back or CB sheet). The lowermost sheet is coated on the top surface with a clay that quickly reacts with the dye to form a permanent mark (Coated Front, CF). Any intermediate sheets are coated with clay on top and dye on the bottom (Coated Front and Back, CFB).