Several properties of black liquor – including residual alkali, temperature, and solids content – are regularly monitored in order to monitor pulping, washing, and evaporation processes at kraft pulp mills. Residual alkali is monitored during cooking to ensure that sufficient residual alkali is present and prevent lignin redeposition. Weak black liquor, strong black liquor, and heavy black liquor solids are observed to monitor washer, evaporator, and concentrator performance, and ensure consistent solids contents to the evaporators and recovery boiler. Other analyses, including heating value, elemental, inorganic, and organic analyses, are used for research, design, and troubleshooting purposes.