In article ,
Ian Stirling writes:
Chris Bacon wrote:
Ian Stirling wrote:
Surprised to find large quantities of "2 for 1" 99p 18W/100W CF bulbs
by Philips, in Morrisons.
They claim 7000 hours.

IME all "CF" lights, the sort that replace incandescent ones,
are rubbish. Why does the output drop off so quickly? Why do
they take time to brighten fully?

The second one is partially due to reducing the amount of mercury in
them.

Also, they are mostly designed to run with a tube wall temperature
of 100C, which is quite a bit different from the 20C when you
first switch them on. Traditional fluorescents are designed to run
with a tube wall temperature of 40C, which is not so different from
the initial switch-on temperature, so the initial brightness is not
so far off the final brightness.

--
Andrew Gabriel