I often see cars with tinted rear windows that have hundreds of bubbles trapped between the glass and the tint film. What causes this?
Is there a factual answer? I’d assume the car owner did it themself.
Or some clown who sets himself up as a window tinter out of his garage.
Both explains the “limo tint” on all windows including the windshield.
Usually some combination of poor glass preparation, poor installation, and poor quality film.
Said another way, there are lots of aftermarket tint jobs that are excellent. I have one.
You (any you) only notice the shittilly done ones.
So your question really ought to be “Why / How are some tint jobs badly done? How could they be done better?”
It’s not necessarily indicative of an amateur job. If happened to the factory tint on one of my vehicles.
Fair.
Can you elaborate on this? If I get bubbles in a tint job, what specifically would I need to do differently next time to get a bubble-free result?
Make sue the tint is squeegeed very well. No water pockets trapped between the tint and the glass.
I see professionals use soapy water between the tint and the glass. I assume the reduced surface tension helps somehow.
It lets you get the film exactly positioned, and wrinkle-free. But, it needs to be squeegeed very well to get all the water out. This is the same technique vinyl-sign makers use - there is a whole array of fluids and tools for making the job easier.
The importance of this cannot be overstated.
When the car is parked in the hot sun, the adhesive will soften from the heat. If it softens too much, the film can separate from the adhesive. The defrost lines in the rear window can make things worse. They protrude slightly from the glass and may allow a slight gap to form between the film and the adhesive. Once the bubbles start to form, then they quickly get worse. It may be very difficult to apply tint to the back window. It typically has a steep slope and the back shelf makes it hard to get back there to apply the tint perfectly.
One reason people may not get it fixed is that the shop may charge $100+ just to remove the tint. And in the summer, there may be a multi-week wait to get in. So until it gets bad enough that they can’t see out the back, someone may just decide to live with it.
I would imagine one of the biggest factors here is practice.
My Anectdote: I’ve done it three times. I’ve noticed a correlation between the size/tightness of the roll with quality of the outcome.
The two times I used the stuff you buy in a box that is rolled like wrapping paper, the jobs turned to shit. The film just wanted to revert to being rolled up! The time I got stuff off a huge roll, and the sheet was nearly flat when laid down, the job turned out perfect, and remains perfect to this day, about 30 years of the truck sitting in the hot desert sun.
It may have also helped that said vehicle is a 1965 model, and the glass (except windshield, which of course I didn’t tint) is all perfectly flat.
One contributing factor might be that a slanted back window gets more solar energy than a vertical side window. Even if the tint is applied exactly the same to both windows, the back window will get more direct sunlight and that may contribute to a quicker degradation of the tint and adhesive.
also, if the rear window is 3D-curvy (99% are) and you apply the tint to the inside (99.9% do), and then the plastificants (the part that keep the floil flexible) evaporate over the span of many years, leading to lower volume/more tension … the foil will tend to pull away …
way more noticable to the rear window than the side windows which are way more 2D / flat