What happens when hard rubber is heated?
Hard rubber will not melt or shrink when heated; instead, it will progressively lose its hardness as it gets hotter, becoming more like regular rubber. While in this state, it can be stretched or compressed, and if the tension or pressure is maintained as the material cools, the deformation can be “frozen” in place. Heat the object again, but in an unstressed state, and it will return to its original shape. Although overheating will scorch it, hard rubber is very heat-tolerant, with a broad working temperature range for heat-molding. For this reason, it was and remains an ideal material for fountain pen sections and feeds, and as a base for metal overlays.
