After putting an eight minus green filter on a H600Fc IV I saw it losing its effect quite rapidly, like after one or two runtimes. This prompted me to switch to Zircon filters as they are supposed to be more durable.
Since then I got a spectrophotometer so I decided to test their durability.
For this I use an YPL Unicorn 1.0 (LH351D) which has a maximum output around 800lm, and a sustained output around 400lm.
It has a PID thermal regulation and the head surface temperature stays constant around 40°C, the filter is placed in front of the TIR optic, there is no glass lens on this flashlight (possibly the filter is at a lower temperature this way).
The light is plugged to a bench power supply so it can be powered indefinitely.
I measure the spot chromacity (CCT and Duv) and illuminance (lux) at 30cm at low output (level 2/5) when the flashlight is at ambient temperature so that the chromacity measurements aren’t affected by the temperature.
I power the flashlight on level 5 for an amount of time, then turn it off, wait for it to cool down (with a fan to speed it up) then measure…etc.
Results :
The classic filter loses strength quite rapidly but then degradation slows down. As a result some more light passes the filter but it’s not proportional.
The Zircon filter barely degraded in 10 hours.
Edit : ran the Zircon for 30hours and it shows a bit of degradation.