"John Robertson" wrote in message
...
On 2017/06/26 2:18 PM, wrote:
On Monday, 26 June 2017 20:59:17 UTC+1, Ian Field wrote:
tabbypurr wrote in message
...
On Sunday, 25 June 2017 22:11:59 UTC+1, Ian Field wrote:
wrote in message
...
Yeah, another Googler. I am oe but I do not drege up decades old
posts,
I
just use it because...

But the thing is you are really not supposed to din halogen lamps
because
then the halogen is not sufficiently activated to allow the filament
to
operate in the higher range, which is the whole idea of halogen
lamps.

Its all about the; "halogen cycle" - vapourised tungsten recirculates
and
condenses back on the filament. Under a critical temperature, it
deposits
on
the inside of the envelope just like regular bulbs.

but slowly. And when full powered it then cleans itself.

You'd have to get the quartz envelope seriously hot to do that - like
glowing so white it gave off UV.

AIUI they're self cleaning at rated voltage.


When they are RUN at the rated voltage and power. If you dim them the
tungsten is deposited on the quartz and short of heating the quarts to
white hot (above poster's remarks) the tungsten is going to STAY on the
quartz, not recoating on the filament.

http://www.topbulb.com/blog/dimming-...halogen-cycle/

In other words don't do it.

I wouldn't go so far as "don't do it" - if you're dimming it, a little
shading probably isn't that much of a problem anyway.

The manufacturers say "don't do it " to cover their asses.