📓 The purpose of this study was to investigate the effects of process and wet-end variables on internal sizing system of Alum and Cationic Rosin and to compare about cost effectiveness of the system with other ones: PAC-Cationic Rosin and AKD, also between systems using different chemicals to control pH (Alum, Hydrochloric acid and Sulfuric acid). In addition, basing on understanding gained from above, a recommendation for a particular case was also brought out.