How long can a gel sheet last inside a par can?

The life span of a gel sheet will vary depending on the gel’s color, the type of bulb and PAR can being used, light intensity, and duration of light exposure. You can estimate the life span of your gel sheet with a little basic knowledge of color gels and light. Darker colors gels, like dark blue and dark green, will typically expire more quickly because they absorb more infrared energy from the light shining through the gel. Depending on how high or low you run your dimmers and for how long, you can approximate the life of your gels.