What minimum light transmittance must window tint material maintain in the visible light range?

The correct answer is based on regulatory standards that dictate the minimum allowable light transmittance for window tint materials in the visible light range. In many jurisdictions, the minimum light transmittance for front side windows is set at 28%. This means that the tint must allow at least 28% of the visible light to pass through the window.

This standard is established to ensure that visibility is not significantly reduced, which is crucial for driver and passenger safety as well as for law enforcement. A higher level of light transmittance helps ensure that the use of window tint does not impede a driver's ability to see clearly and allows law enforcement officers to effectively see into the vehicle if necessary.

Standards can differ by region and for different windows (such as rear windows versus front windows), but maintaining a minimum level of light transmission is a common requirement across many areas. Hence, 28% is often recognized as the minimum standard for effective visibility while still providing some level of tint for privacy and UV protection.