The use of wood to produce paper was started in USA Additives such as rosin(松香) and alum(明矾)Were added to strengthen paper and make it accept ink well Chlorine as used to bleaching paper and titanium dioxide (钛白粉) was used to make the paper white. Acidic paper, acid-free paper and alkaline paper Plants alternative to trees: willow(tp), kenaf(K). They usually have high fiber content and grow fast 70 million tons of paper are used in USA: one person 230 kilograms or six trees• The use of wood to produce paper was started in USA. • Additives such as rosin (松香) and alum (明矾) were added to strengthen paper and make it accept ink well. Chlorine as used to bleaching paper and titanium dioxide （钛白粉）was used to make the paper white. • Acidic paper, acid-free paper and alkaline paper • Plants alternative to trees: willow (柳), kenaf (麻). They usually have high fiber content and grow fast. • 70 million tons of paper are used in USA: one person 230 kilograms or six trees