P-49 is a tall oil modified phenolic novolak. It does not contain hexa and is the base resin used in the manufacture of P-55 resin. P-49 is used primarily in SBR stocks where high processing temperatures are encountered. Modification of the phenolic resin with a mineral oil improves SBR compatibility and dispersibility. This is the base resin used in P-55, but without hexa in it as received. Use of this resin allows full advantage to be taken of its strong plasticizing action during processing without fear of scorching. The hexa can then be added late in the mixing cycle or on the warm up mill to make the resin properly thermosetting on cure.