Why some colors kill your output

A deep-blue gel is a filter that throws away almost the entire lamp. Lee 181 “Congo Blue,” the beloved deep blue of theatre, famously transmits only a few percent of the light that hits it — the rest becomes heat in the filter. That's the subtractive tax.

LEDs pay a different tax. An RGB fixture makes saturated primaries brilliantly but struggles with pastels and convincing whites, because it only has three narrow emitters to work with. That's why better fixtures add emitters — RGBW (white), RGBA (amber), up through six-plus-color engines with lime and UV — to fill the gaps in the spectrum. More emitters, better skin tones, better pastels. Know your fixture's engine and you know which of GEL's pastels it can actually make.