About Functional Film Please let me know if RAY-BARRIER would have scratch, or degradation, or peeling on cleaning. We don't recommend applying RAY-BARRIER on old degraded, scratched, or wired glasses. Rising temperature of the film may cause the glass to break. Can I apply RAY-BARRIER only for the purpose of UV shielding? The properties of RAY-BARRIER are to shield ultraviolet ray and HEAT. So if you applied it for only shielding UV, the other feature will also be present. On which side of window, should RAY-BARRIER be applied? Inside or Outside? Please apply RAY-BARRIER inside of the window. Are there any restrictions on detergent used for clean up? Please clean up with a moist towel. In case of heavy dirt, please use mild detergent with wet towel. After applying RAY-BARRIER, compared with plain glass, does window glass become visibly stained or scratched by daily cleaning? Would clearness of glass be affected by applying RAY-BARRIER? Our research shows that RAY-BARRIER has 80% of visible light transparency (glass itself has 90~95%), and 1~2 defog (5 on normal PET film). It is difficult to find the difference with the naked eye, however clearness is lost. Regarding durability, RAY-BARRIER is film; therefore it is weaker than glass itself. For avoiding scratch, RAY-BARRIER is hard-coated. However its hardness is only H~2H (caused scratch by scraping H or 2H pencil). There is no harm for daily clean up, but if you treated it the same as glass, it may cause scratches, which may cause loss of transparency.