Last October I replaced the bathroom window and applied a self adhesive film to simulate the original frosting of this window. Although promised differently by the supplier the foil did not like the temperature changes and contraction and expansion of the Makrolon much. Bubbles have formed behind the foil leaving the window looking quite bad. Thankfully I did not attach the foil inside the airgap. I will have to come up with a different way to frost this window.