Heat transfer experiments with a saturated CaSO4 solution were carried out in a closed-loop test rig containing an externally heated test section. Reproducible fouling curves were measured for the solution without fibers. The buildup of deposit was asymptotic, which implied that the fouling process was a combination of crystallization and particulate fouling. The addition of a small quantity (less than 0.05 mass percent) of softwood chemical pulp fiber to the bulk reduced the rare of fouling significantly. At 0.05 mass percent fiber-addition, no fouling was measured in the rest rig during 7 days of continuous running. The addition of fibers reduced the rare of deposit buildup and potentially offers a new method of fouling mitigation. Only a low concentration of fibers is needed, and the nontoxic fibers are easily removed.