How to Apply Window Film in 9 Steps

Some window film installation kits come with their own application solution that you can use to clean your windows and apply the film. But if there’s no application solution in your kit, you can easily make your own.

Mix 1 teaspoon of baby shampoo with 1 gallon of bottled water. The distinctions here are important: Baby shampoo and bottled water will provide the right pH needed for the application.

Pour the solution into a spray bottle, then spray down the entire window. Use a shower squeegee to thoroughly clean the glass. After each complete “squeegee motion,” wipe off the squeegee with a clean, non-linting cloth (like a microfiber towel) to ensure you aren’t just pushing dirt and dust particles around the window.

After squeegeeing the window, spray it down again, and take a new paint scraper to the glass. There can be minute flecks of paint, dirt, and dust that you can’t see that could affect the installation, so scrape the entire window, even if it looks completely clean.

Finally, clean around the window frame. It’s very possible that while squeegeeing the glass panes, you inadvertently send dirt and dust to the edges of the window. Take a clean cloth and wipe down all the edges of the frame to remove any lingering particles.

Measure your window (or individual panes for more complex windows) and cut the window film to size. It should be 1 inch wider and 1 inch longer than the dimensions of your window; it’s best to have a friend or family member double-check your measurements so you can confirm they are accurate.

• Straight windows: Straight windows are easy to measure; you’ll want to measure the width from left to right, and then the height from top to bottom. 

• Round windows: Round windows are rare, but if you have one, you’ll need to measure the circumference (the outer edge of the circle), the diameter (the measurement across the inside, center, from edge to edge of the circle), and the radius (half of the diameter). A formula to calculate the surface area of a round window is A=πr2. (π=3.14).

• Curved windows: Curved windows are difficult to measure; to get an accurate measurement, it’s best to call in the help of a local window installer.

You’re almost ready to apply the window film—but you need to spray down the glass again. The solution you created (or that came with the kit) is crucial to adhering the film to the glass.

Adhere two pieces of clear tape to a corner of the window film piece you cut—one piece of tape on each side. The tape will give you leverage to begin peeling the window film from its release liner (the backing of the window film).

As you peel off the window film, liberally spray the adhesive side that will lay on the glass. It’s helpful to have a second person manage the spray bottle as you peel back the film. If you don’t have a helper, lay the film on a clean surface as you peel it; you want to ensure no dirt or dust particles land on the adhesive side.

Note: The key difference between how to apply non-adhesive window film and self-adhesive window film is that, for the former, you do not need to spray the film as you peel off the release liner. As long as the glass itself is wet, you should be fine. For self-adhesive, you need to be more careful when peeling off the film—you don’t want dust, dirt, or any other particles to attach to the film before application, which is why you must spray it as you peel.

Carefully apply the film to the glass, starting at the top. If this is the first piece of film you cut, there will be a straight factory edge that you can line up plumb with the top of the window. Otherwise, install it so there’s a slight overhang past the top of the window.

Continue to work your way down the window, gently applying the film. Ensure that it slightly overhangs the sides and bottom of the window.

Once the film is completely laid against the glass, spray it down with solution. Then, use a plastic card squeegee (many kits come with these) to push the water bubbles out. Start from the center and push outward with the squeegee, stopping roughly 1 inch from the edges. Continue to spray the film as needed to keep it wet while squeegeeing.

To trim the window film, take your 5-in-1 tool to a corner of the window and use the tool to press the edge of the film against the window frame. Then take your utility knife and, starting from the corner, begin to trim the film. Move the utility knife and 5-in-1 tool along the frame together until you’ve trimmed the entire side. Repeat for the other three sides of the window.

Grab the plastic squeegee one more time. Spray down the film again and use the squeegee to push out any remaining bubbles. This time, you can force the water out to the edges. Cover the squeegee with a microfiber towel so that it catches any excess moisture as you push it out of the edges of the film.

Once the moisture is completely gone, voila! Your film is finally installed.

Note: You may be tempted to clean your window film shortly after application, but it can take several days or even weeks for the film to bond completely to the glass. Wait at least 30 days before cleaning.