4 min read
Tint brochures are full of big percentages, and most of them are measuring different things. If you want to compare two films honestly, you need to know which number you are looking at. Here is the plain English version.
VLT, how dark it is
Visible light transmission is the percent of visible light the film lets through. It is the number Georgia law regulates and the one people mean when they say 35 or 20 percent. It tells you how dark the film looks. It tells you almost nothing about heat.
UV rejection, the easy one
Nearly every quality automotive film blocks 99 percent of ultraviolet light, including the clear ones. UV is what fades your dash and damages your skin. Treat 99 percent UV as the baseline, not a selling point.
IR rejection, the number that gets abused
Infrared is the part of sunlight you feel as heat on your skin. Infrared rejection numbers in the 90s sound impressive, but they usually measure a narrow slice of the infrared spectrum where the film performs best. A film can post a 95 percent IR number and still let a lot of total heat through, because sunlight's energy is spread across visible light, near infrared, and ultraviolet, not just one band.
TSER, the honest number
Total solar energy rejected is the share of all the sun's energy, across the whole spectrum, that the film keeps out of the car. It is the single best predictor of how cool a tint will keep your cabin. Dark dyed films often land in the 30s or 40s. Quality carbon films do better. Ceramic films are where TSER climbs into the 50s and beyond, and they can do it at light shades because they reject infrared without needing to be dark.
Why a light ceramic can beat a dark dyed film
A 5 percent dyed film blocks almost all visible light, but visible light is less than half of the sun's energy. A 70 percent ceramic lets most visible light through and still blocks a large share of infrared, so its TSER can be higher than the limo dark dyed film. That is the whole reason ceramic exists, and it is why we recommend a light ceramic on the front doors when the goal is heat, not looks.
How to compare two quotes
Ask each shop for the TSER of the exact film and shade they are quoting, not the IR number and not a marketing phrase like total heat rejection. If a shop cannot tell you the TSER, that tells you something too. We publish the film brands we install on our tint guide and will show you the manufacturer spec sheet for any film in the shop.
Feel it before you buy
Spec sheets are useful, but the heat lamp in our shop is faster. We hold the films we install under a lamp and let you put your hand behind each one. The difference between a dyed film and a ceramic is obvious in about three seconds, and that is usually the end of the debate.