The following write-up is an article S. Lucas Valdes (President & Resident Mechanical Engineer of GoWesty) wrote to provide some info window tinting.
First, four disclaimers:
1) My comments are specifically related to 1968-2003 VW Campers!
2) I am not a window tinting expert.
3) The data given below is the best I have been able obtain; the rest is my opinion.
4) My opinion is that I HATE after-market window tinting!
OK, here is the scoop on after-market window tinting. The % given for a particular tint is the amount of light that is let in, not the level of darkness of the tint itself.
A 5% tint is the darkest available. It lets only 5% of the light in. This is your classic gangsta limo tint.
The next step up is a 15%-20% tint, still quite dark, looks black at night, hard to see through when backing up at night.
The next step is 30-35% tint, which is quite mellow. In bright light it's hard to tell that it is there, still too dark to be legal for front windows, but the practice is common place.
The next lightest is 50%, hard to tell any tint is there at all, but it is still illegal for front windows.
The lightest "tint" is 70%, but is practically invisible. Even still, it is not legal for front windows. Then there is 90% which is basically clear with UV protection only, and is the only legal "tint" for front side windows, but not really. An expert recently wrote the following: "...The only true legal window film for California would be about an 90% clear UV film, the actual law states, 'The film and glass must block no more light than police patrol car windshields which is 70%... today's glass is tinted to 70% already...'" A statement which appears to be contradictory... One thing is for sure: No tint at all is legal for the windshield. I think everyone agrees on that! Original, factory glass on all Vanagons and Eurovans, and most 68-79 Buses, is tinted (contrary to popular belief). Truly "clear" glass went out in the 60s. The existing factory tint is about the same as clear glass with 70% tint on it. Except, factory glass has a bit of green or blue color to it. Aftermarket tinting is more of a brown or gray color.
At GoWesty: We do not offer any aftermarket window tinting. Period.
These are the reasons I hate aftermarket window tinting:
1) I don’t like how it impairs vision at night. The lighter stuff not as much, but all of it decreases visibility at night. I have trouble seeing at night as it is, with no tint at all.
2) This stuff is not glass; it’s plastic and scratches very easily as compared to glass. When applied to moving windows, like the front doors or center sliding windows, it will scratch over time. Just how quickly depends on how much you open and close that window. Even on fixed windows, just cleaning it over time will scratch it unless you are very, very careful. It will eventually become so scratched and “foggy" that it will be useless and will have to be replaced. The new stuff that is out there is WAY better than the days of old, but hey, it is still plastic and it WILL scratch. Heck, we see GLASS with scratches in it!
3) It is expensive when done correctly. To do a really nice job, especially on a VW camper, the windows really should be removed so the stuff can be applied all the way to the edges of the glass. That way, when installed in the vehicle, the rubber seal completely encapsulates the edges of the tinting material, thus preventing it from peeling, and totally eliminating any edges so that it looks like factory tint. While it is true that most installers will guarantee the materials for life, it is unlikely they will agree to remove and install the glass on the second application, and for sure another installer across the country will not honor the warranty even if they use the same brand stuff.
If you live in a place where there is 24-hour intense sunlight, you never roll your windows down, and you never clean your windows, then I say go for it. Otherwise, give me good ‘ol factory tinted GLASS!