# Estimating IRC with the Grease Spot Test



## Roger44 (Dec 27, 2009)

hello
The other day, doing a "grease spot test", I noticed the transition of the spot from bright to dark was very sharp when comparing icandescent, including halogen, and CFLs between each other.

However when comparing an 8 watt white LED array and a 40W incandescent source, the transition was very uncertain with the spot taging on a reddish coloration.

Same thing with a T4 22W fluo tube, this time the spot took on a green-blue hue during the transition from bright to dark.

It's a bit premature to jump to conclusions with the only LED lamp I've got, but I'm wondering to what extent the "grease spot test" enables a rapid assessment of IRC.


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