Abstract: Devices and methods are provided to characterize local, small-scale variations in tack build-up, e.g., by measuring tack over areas smaller than 20 mm.sup.2, preferably over areas smaller than 1 mm.sup.2. These devices and methods measure the tack properties, e.g., tack build-up, of a coating over a very small area, allowing characterization of such small-scale variations. The invention also provides methods for using such characterization to predict back trap mottle (BTM).

Abstract: A method is described for monitoring and determining the degree of completion, pulp yield, and residual lignin content in a pulping or delignification reaction. The system provides an on-line, real time, closed loop process control system for the reaction of a known quantity of wood in process liquor. The desired pulp yield is achieved by sampling the liquor during the reaction; determining the total organic carbon content of the sampled liquor; and calculating the degree of completion of the reaction and pulp yield from the process liquor total organic carbon content determination using an appropriate mathematical model. The mathematical model is based upon conservation of carbon mass in the wood or pulp and liquor during the reaction, and includes a conservation of mass equation in which the total organic carbon in the sampled liquor substantially equals the total carbon in the starting quantity of wood or pulp less the total carbon in pulp wood residue at the time of sampling the liquor.