Kapton is a polyimide film wich can withstand a wide range of possible temperatures from -269°C to 350°C. Therefore, it is an optimal material to cover the printing bed of a 3D printer. You might have seen the thin yellow foil on some 3D printing beds before. Kapton can be bought as a tape or foil, both come with a sticky side, ready to be put onto the glass surface of your printers pad. However, when applying the Kapton tape or foil to a glas surface, you often end up with bubbles – at least it happens to me. Since the sticky sides sticks very well, it is almost impossible to get rid of the bubbles, which defies the purpose of having a nice smooth surface for your prints.
The best way to apply a Kapton foil without bubbles is the “Wet method”. By applying a thin layer of detergent and water onto the glass surface, the Kapton tape sticks a bit less in the beginning, which allows you to remove any bubbles that may form on the adhesive side with a ruler. I made a video of showing the overall procedure.
Thanks to Sriram for the camera work! You can spot him at the end of the video.