What does IR rejection measure?
The share of solar infrared kept out of the car. Infrared begins where visible light ends, so you can’t see it, and LLumar’s performance data sheet measures it from 780 to 2,500 nm. 3M’s Color Stable brochure describes infrared as “primarily responsible for the heat you feel when driving.”
Because infrared is invisible, a film can block a lot of it while staying light. That’s the whole idea behind LLumar’s IRX: its IRX page says the film’s nano-ceramic is aimed specifically at infrared heat.
IRER, SIRR and IRR: which number is which?
Three labels, three different counts. The table sets out how each maker defines its figure:
| Label | Used by | Band | What it counts |
|---|---|---|---|
| IRER, IR energy rejection | LLumar, 3M | 780 to 2,500 nm | Infrared kept out, after counting absorbed energy that radiates back inside |
| SIRR, selective IR rejection | LLumar | 780 to 2,500 nm | Infrared “not directly transmitted through glass” |
| IRR, infrared rejection | 3M | 900 to 1,000 nm | A narrow slice of the infrared band |
LLumar’s footnote calls IRER “a more complete measurement of heat experienced.” On its sheet the gap between the two is wide: IRX 15 posts 61% IRER and 88% SIRR, and AIR 90 posts 40% and 57%. Quote either one by name, never as plain “heat rejection”. For the figure that adds visible light and UV to the count, see TSER.
Why IR rejection matters on a car in BC
It’s how a film keeps heat out without going dark. BC lets film go on any glass behind the driver at any shade, so the choice between dark and light is yours, and infrared rejection is what lets a light film still cut heat.
On LLumar’s sheet, clear AIR 80 passes 77% of visible light yet holds back 60% of infrared energy, the same IRER as IRX 05 at 6% light. Dyed ATC, by contrast, holds 22% IRER in every shade, so going darker in ATC buys privacy rather than infrared control. Seeing out through dark glass after sunset is a separate question, taken up in dark tint and night driving.
Where IR figures show up on the shop’s pages
On the IRX and AIR film pages, in the heat rejection comparison tool and on clear heat rejection film, the service for drivers who want the infrared cut without the dark look. IRX and AIR are both quoted as upgrades on the dyed ATC rear packages, and most cars leave the same day.