When the importing of ivory was outlawed to curb the illegal slaughter of elephants, the ban eliminated the markets for ivory jewelry, sculpture and decorative household items. But it also forced a change in a less obvious area - piano keys.
Playing on the plastic keys that replaced ivory ones quickly proved to be frustrating for pianists. Many did not like the feel of perfectly smooth plastic and found their fingers slipped because the synthetic keys didn't absorb moisture from perspiration.So, Steinway Musical Properties Inc., the pianomaker, turned to the Renesselaer Polytechnic Institute in Troy, N.Y., to develop a better plastic key. A group of engineers there, who usually study the sliding or movement of surfaces as they relate to bearings and seals, examined old ivory keys under a scanning electron microscope.
Now they've won a patent for an ivory substitute for piano keys.
"We measured the surface roughness" of ivory keys, said Salvadore Calabrese, one of the seven engineers named in the patent, "and the height of the peaks and valleys, and how the peaks and valleys are oriented to each other."
The orientation turned out to be random. The pores in the ivory, which absorbed moisture, were random, too.
"We ended up using the ivory itself to make a mold, so we duplicated the surface exactly," Calabrese explained.
The engineers tested several kinds of plastic to "evaluate the friction against fingers," Calabrese added. They settled on polyester mixed with water-soluble wax beads. After the resin sets, the wax beads are washed out, leaving pores.