Chemical pulping involves dissolving the lignin by using heat, pressure and pulp and paper chemicals. This process results in stronger paper which is less likely to tarnish. Chemical pulping machines are used to make stronger paper. They are used to produce high-quality papers as the chemical cooking dissolves most of the hemicelluloses and lignin present in the wood. There are several different process to be followed and sundry chemicals are used to carry out chemical pulping. Some of them are caustic soda, sodium sulphide, sulphurous acid etc.