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What makes the Window film bubble?

bubbles in sun protection films

Small, miniature pea-looking bubbles form under the window film, when the moisture under it condenses into water drops.

You often hear that installing windows films by yourself is difficult, because bubbles form so easily between the window and the film. This isn’t the whole truth, as installing the window films yourself isn’t too difficult — especially if you have quality window film, , quality tools and guides..


What are these notorious bubbles?

In ordinary language the word ”bubbles” can be used to denote a few things. It can mean small, circular, slightly pea resembling light bubbles, that may form during the installation of sun protection films.

These particular bubbles form if something redundant, usually dust, has found its way between the glass and the film. Dust, hair and other dirt stop the window film from attaching and thus form a bulge in the film. The air trapped under the film makes the dust into a bubble. The air can usually be squeezed out by piercing the film with a sharp knife from the point where the dust is situated. This, however, has its risks when it comes to the proper attachment of the film and on top of that it leaves an uneven spot in the film. For that reason particular attention must paid to cleanliness when installing window films.

Avoid the bubbles caused by dirt by doing the following:

  • Clean the windows carefully with a tuft-free cloth, squeegee the windows twice, just in case and avoid touching the adhesive side of the window film.
  • Also thoroughly clean up the sealing of the glass.
  • Make sure your hands are clean when working with the window films, and touch the adhesive side only with dry hands (and even then, only the very edges). Wet hands spread more dirt than you would believe, even if they look clean.
  • Finally, squeegee the window film well and remove as much moisture as possible from under it.


We can also refer to bubbles, when we mean moisture, that is yet to evaporate from under the window film.

This is very common and is no cause for concern. Even the best squeegee cannot remove all the moisture. The moisture stuck under the sun protection film condenses together, often forming different kinds of bubble-like areas, the surface of which can differ widely.

The window film is made out of porous material and it lets the moisture evaporate through itself slowly, while simultaneously removing these so-called bubbles, while the film is still attaching to the window.

The weather greatly affects the drying time of sun protection films. In hot sunny weather the adhesive of the window film may dry completely in couple days, but during cold fall or winter weather the drying may take several months.


The other ”bubbles”

Bubbles may also be used to refer to the air or water remaining under a film as it is yet to be squeegeed out. In this case these bulges result from the sun protection film being yet to be installed properly and completely.

Quick guide for installing the Window film

The window film is installed on to car windows by shaping, cutting and shrinking it to the right size on the outside surface of the car window. For this purpose you must first spray soap-water solution on to the windows and the adhesive side of the sun protection film. Then the film, cut to right size and shape, is placed on top of the windows. After that, its time to squeegee out the air and water trapped under the film, starting from the middle of the film and making your way towards the edges.

When installing the windows films on flat surfaces, such as the rear side windows, squeegeing the soap water and air out is easy. It becomes hard when the installation has to be done on a curved surfaces, such as the rear window. With them the mere use of a squeegee isn’t sufficient (its isn’t always sufficient with side windows also), as the film has to be evenly shrinked on to the window with the use of heat. This may prove to be difficult for many.

Start by carefully washing the rear window of the car, both from the inside and the outside. Spray the window completely with the soap-water solution. Place the sun protection film on the outside of the window and cut it into to the approximate shape of the window. After that shape the film by shrinking it on the outside surface on the windows, with the film being ”upside down” (liner of the window film pointing outwards from the window) and without removing the liner from the window film.

Heat the bulges (always from middle to top or bottom, never sideways!) with a heat gun/hair dryer while using the squeegee to remove air beneath the film and try to make the film shrink to the shape of the window. Heat bulges starting from the middle of the film. The film, when heated, forms zigzag-like shapes on top of the bulges. Then immediately squeegee these shapes towards the edge of the sun protection film.

Proceed calmly, as you may have to heat and squeegee the bulge several times before getting completely rid of it. You should also divide big bulges into smaller ones to balance shrinking around the film. 

After a while, you’ve probably got the film neatly fitting on top of the window. Remember to pay attention when using the heat gun, as it can accidentally burn the adhesive coating of the window film, if you heat the same spot for too long. Also remember that the window film only shrinks to vertical direction of film roll.

The next section, which is the actual installing of the window films, takes place inside the car. Remove the liner from the window film and spray soap water on the well-cleaned inside surface of the car window as well as on the window film. Place the film carefully on to the right place and start to squeegee out the air and soap water under the film — starting from the middle, making your way towards the edges.

The film is installed, when its perfectly moulded on to the glass, and when there is no excess air or soap water underneath it.

Check precise and detailed instructions for installing the windows film from here.



When referring to bubbles, what is meant can be small round bubbles, which are caused by dust or other dirt remaining on the window. They can be avoided only by paying close care to the cleanliness of the working area.

Bubbles are also used to refer to darker, grey areas, which are caused by moisture condensing into bubbles under the film. These bubbles usually disappear within few weeks, if the window film is properly installed.

Bubbles can also be used to refer to the situation where the window film doesn’t properly shrink on to a curved glass. When this happens, the reason behind it is that the sun protection film isn’t properly moulded and shrank on the outside of the window by using a heat gun. Shrink the film by using heat first on the outside surface of the window, when it is easier to install on to the inside. Take note, that the window films only shrink in the vertical direction of the film roll.

An important factor for success when installing window films on curved windows is the ability of the film to shrink. Cheap window films usually shrink nowhere near as well as the window films from quality name brands. All sun protection films the we sell have great shrinking capability, so installing them would be easier!

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