Appearance of air bubbles after a few hours

After being flat I had no worries to place correctly on a clean, flat surface. The record was perfect ... but did not last. After a few hours of air bubbles began to appear and over time making itself increasingly large and increasingly numerous. Unable to recover sustainably the initial rendering, even removing and repositioning the table. So I finally remove it and throw it away, which is a shame considering the price.
I absolutely do not recommend!