To properly use OCA here is the method I use. lay oca sheet on glass slowly roll it on from bottom working your way to top. Make sure the oca sheet is pressed up against roller as your laying it or it will get airbubbles. do this rather lightly as to not smudge the oca sheet causing bubbles and damage to the glue. next lay the oca sheet with glass on the lcd and line up correctly. then i gently press in the corners and use the roller on the back of the lcd pressing from the bottom working your way to the top. Using a lot more pressure than before, do this slowly. I also force the roller torwards the corners. Next place it in Autoclave for 10 minutes at 70c. if done correctly there will be no bubbles. if there is place on a hot pad at 95celsius for 10 minutes then throw in back in the autoclave for 20 minutes at 70 c. ask for questions i do this for 40 hours a week refurbishing phones all day.