The paper you use is usually white because it has been bleached by a chlorine-based bleacher. Bleaching paper is harmful to the environment. In fact, chlorine-intensive bleaching is claimed to be one of the worst sources of water pollution. According to treecycle.com, bleaching terms are often misused, although there are significant differences among them. Totally chlorine free (TCF) means that no chlorine or chlorine derivatives are used to make the paper. It comes from virgin (new) fiber. Elementally chlorine free (ECF) means that no chlorine was used, however other chemicals containing chlorine are used for bleaching. ECF paper is often misrepresented as TCF. Process chlorine free (PCF) means that recycled paper that is processed back into paper using no chlorine or chlorine derivatives. The paper is either not re-bleached or is bleached with an oxygen-based system. Secondarily chlorine free (SCF) is the same as PCF.