Due to environmental restrictions, the closing of water circuits and the increasing use of recycled fibres (with a lower quality of the waste papers to recycle), paper makers have an increasingly difficult problem to solve: the deposition of sticky particles either on the sheet forming fabric or on the press and dryer felts. These problems are often very difficult for the paper makers to understand because they can appear without any visible change in the raw material or in the papermaking process variables. In this paper, after a definition of what are called secondary stickier, an attempt is made to analyse and explain these phenomena. The different changes occurring throughout the pulp preparation process and the wet end of the paper machine are reviewed, with special attention paid to the changes affecting the destabilization of the pulp suspension, i,e., to the formation ol secondary stickies. The main characteristics involved in the stability of a pulp suspension are reviewed and a test method to characterize the potential of the pulp or the process water to produce secondary stickies is presented. Results obtained with this new test show clearly the strong relationship between destabilization and the formation of secondary stickies. Additional experiments show that the paper machine's wet-end chemistry also has a strong influence on the deposition.
