On 17/10/2011 17:07, Simon Finnigan wrote:
"Phil wrote:
Simon Finnigan wrote:
Hi everyone,
Ive painted a few rooms with a paint that under daylight is a lovely
warm happy yellow colour. Under energy saving bulbs it looks the
brightest day glow yellow you can ever imagine :-)


You didn't buy it from someone caled Trigger did you?

It's B&Q branded, looked lovely in the shop, looks lovely during the day,
but once the CFL bulbs come on it looks glow in the dark. It's bloody
weird!

Well its not *that* weird... ;-)

If you look at [1.3.3] (then compare with [1.1.1] at the top:

http://ioannis.virtualcomposer2000.c...ci.html#1fluop

You should see a breakdown of the typical spectrum for a CFL. These are
usually characterised by lots of missing bits, with a number of
predominate "spikes" in output at various frequencies.

Chances are your nice yellow paint reflects a range of frequencies
centred about the yellow portion of the spectrum. With natural daylight
(i.e. when the paint is reflecting light from a full spectrum source) it
looks ok. With CFL illumination the paint will still reflect the same
range of colours, however most of the ones that add up to give the
characteristic you see in daylight, are now missing from the source. So
you will instead see just the few spikes in output that the bulb can
produce at frequencies not absorbed by the paint. This loses the
subtlety of the colour.

Look at:

http://www.jasonmorrison.net/content...-incandescent/

See how the CFL output has a very "flat" or "solarised" look in the
green regions, and very low intensities in much of the yellow. Hence
nay nice subtle colour that includes a fair amount of green/yellow is
likely to be rendered with most of the yellows attenuated, and all
subtle variations of green reflected as one flat colour.

--
Cheers,

John.

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