ROSIN SOAP SIZING WITHOUT MORDANTS BY IMMERSION IN SIZE SOLUTION

Dipping handsheets in rosin soap solution and drying them with heat wi ll achieve effective sizing. No alum is necessary. The drying conditio ns of the handsheets in both pre-dipping and after-dipping stages is c ritical. The concentration of rosin in the dipping solution is also cr itical for some pulps. Heat treatment can promote sizing in TMP and bl eached softwood pulps but not in bleached hardwood pulp. Heating at hi gher temperature for more than one hour can develop good sizing even i n control handsheets made from chemical pulps containing no rosin but not in the control TMP handsheets. Ester or some acid anhydride linkag es may provide the bonding mechanisms for the rosin size.