ABSTRACT Bleached Chemi-ThermoMechanical Pulp (BCTMP) is widely used in the paper industry due to its lower production costs. This study aims to determine the effect of the use of BCTMP on the dose of colourants, especially Optical Brightening Agent (OBA) and dye violet. Data was obtained from PI (Plant Information) and PMIS (Process Management Information System). The results of the analysis …