A property manager walks past the south side of a Bellevue office building and sees it for the first time. The film on the third floor has turned a faint purple. A few windows near the corner have small bubbles along the edge.
Most people think this is just what old film looks like. That guess is close, but it misses something useful. Purple film and bubbled film are two different problems with two different causes. Each one tells you something about the film that went on your glass and the crew that put it there.
This article explains what happens inside the film and how to read what you see on your own building.
Window film is not one sheet. It is several thin layers stacked together. There is a plastic base layer, a layer that adds color or blocks heat, a layer of glue against the glass, and a hard coat on the side facing the room. Each layer wears out at its own speed.
So when someone says a film “failed,” one layer usually gave out first. Industry guidance treats this as normal wear, not a random defect. Film starts to fail when the glue, the plastic base, or the UV-blocking layer breaks down.
Two of those layers cause almost every problem you can see from the sidewalk. Here is how the signs match up:
The third one matters because people mistake it for dirty glass. Once the plastic base starts to break down, it cannot go back. On our commercial jobs in Seattle and Bellevue, hazy film is the one property managers try to clean off before they call us.
Cheap film gets its dark look from dye mixed into the plastic. That dye is usually a blend of red, blue, and yellow. Mixed together, they read as gray. Sunlight carries enough energy to break the dye apart.
The three colors do not break down at the same speed. Yellow goes first. Take yellow out of a red, blue, and yellow mix, and your eye sees purple. Industry write-ups on this point to yellow as the weakest of the three under UV light, which is why the color lands on purple so often.
Better dyed films add UV blockers that slow this down. Cheap film skips them. That is why purple can show up in the first two years. The color change is not a bad batch. It is what dyed film does in the sun.
Puget Sound gets less sun than Phoenix or Dallas, so we see this problem later here than installers in the Southwest do. It still comes. Glass facing south and west in downtown Bellevue and South Lake Union takes real sun from June through September. When someone calls us about color, those sides of the building are almost always where it started, usually on upper floors with nothing next door to block the sun.
Bubbles start in the glue, not in the film you can see. Window film sticks to glass with a soft acrylic glue. That bond only holds if the film cured properly and the glass was clean on install day.
3 things break it:
Timing is what tells the three apart. Use this table to place what you are looking at:
| What you see | Likely cause | When it shows up | What it means |
|---|---|---|---|
| Small air bubbles | Dust on the glass | Right after install | Prep problem, minor |
| Water bubbles or light haze | Film still drying | First 1 to 14 days | Normal, usually clears up |
| Bubbles that spread, edges lifting | Glue breaking down | Months to years | Film has failed, needs replacing |
The read here is simple. Bubbles in week one usually settle on their own. Bubbles in year four are the glue giving up, and waiting will not fix them.
If purple comes from dye, then film made without dye has no dye to lose. That is the main difference between good commercial film and cheap film.
3M builds its Ceramic Architectural Series with tiny ceramic particles instead of dye. 3M states these films keep the same color and look over time. The line is also metal-free, so it will not rust. All Ceramic Architectural Series films come with a 12-year warranty when a pro installs them on a commercial building.
The Prestige Series gets there in a different way. It uses metal-free film built from many thin layers to block up to 97% of infrared light and up to 60% of the heat coming through the glass. It also blocks up to 99.9% of UV rays. Prestige films come with a 15-year commercial warranty when a pro installs them.
We use these lines on commercial glass because the color question stops being a question. As a 3M authorized dealer, we can answer that part in one sentence. What the film choice cannot fix on its own is the glue. Good film on dirty glass, or film rushed before it dries, still bubbles. Both halves have to be right, and that is a big part of what 3M certification asks of us.
The International Window Film Association is clear about how long film lasts. It depends on the film type, the glass type, how the window is built, which direction the glass faces, and where the building is in the world. The group also notes that all quality films come with a manufacturer warranty.
Read that list backward, and it turns into a checklist. Film that failed on one side of the building but not the others points to sun exposure. Film that failed everywhere at once points to the product itself. Film that failed at the edges first points to the install, or to water sitting where it should not.
There is a bigger version of this problem. The IWFA notes that glass breaks under stress, and that heat stress from sunlight is the kind film can affect. Film makers publish film-to-glass charts for trained installers to follow. If the first crew put dark film on the wrong type of glass without checking that chart, color is the smaller of your two worries.
We check the film-to-glass chart before we quote. Most Seattle buildings have glass from several different decades in them. On those jobs, the chart often changes which film we suggest for each side of the building.
Purple film cannot be fixed. Neither can glue that has already let go. The only real question is when to replace it, and waiting costs you in three ways.
Performance drops first. As the dye breaks down, the film blocks less heat and less UV. You keep the ugly look and lose the benefit you paid for. Removal gets harder next because old glue comes off slower and adds labor to the quote. Tenant reaction is the third, and in nicer office buildings, it is often what finally moves the budget.
Before you pay for anything, check these 4 things:
Bring those four answers to any quote and you will get a much better proposal, from us or from anyone else. The timing also ties into the payback math, which we covered for Seattle and Bellevue office buildings here.
If your building has purple, bubbled, or hazy film, we will come look at it. The inspection is free and takes about an hour on a typical commercial property. You get a written answer on what failed, why, which sides are affected, and what your glass can safely take next.
D&A Customs is a 3M authorized dealer serving Seattle, Bellevue, Tukwila, Renton, and the greater Puget Sound area. See our commercial window tinting services, or contact us to book an inspection.
