Fiber hardener is used to soak blanket or fiber boards to stiffen them and make them produce more than one firing. Also designed to harden fiber paper mold constructions. Apply to the fiber mold with a brush and cure at 175 degrees F until surface is hard. Mold surface can be sanded to a smooth finish. Repeat the process, and the mold will be ready for firing to 1300 degrees F (704 degrees C).