Does Plastic Art Last Forever?

In the early 1960s, curators at the Philadelphia Museum of Art noticed something funny about one of their modern-art sculptures: It smelled like vinegar. Worse, the once-clear plastic sculpture had begun browning like an apple, and cracks had appeared on its surface. By 1967, Naum Gabo's translucent, airy Construction in Space: Two Cones looked like Tupperware that had gone through the dishwasher too often.

The volatile Gabo got so angry at the curators (he blamed the deterioration on their keeping his work in an airtight display case) that he took the sculpture back to repair it. That didn't work—things, in fact, got worse—and he finally gave up. He cast a replica of Two Cones, donated it to the Tate in London, and gave Philly back the degraded original.

(from Slate)

Apparently plastic art does not last forever. So.... do artists change their medium? Does the deterioration become a "part" of the artistic product and process? I really liked this article - reminded me about the factors "behind" the art.