In article ,
The Night Tripper writes:
Hi All
I recently fitted a pair of new light fittings - ceiling things with
3x G9 halogen bulbs in each fitting. Each bulb has an opal glass surround.
The fittings were supplied with (frosted) 40W halogen G9 bulbs.

I'd guesstimated that the resultant brightness would be greater than that of
the old fittings they replaced, but was a little disappointed with the
result. However one of the bulbs as supplied was faulty, so I bought a
replacement pack; 2x 40W clear G9 from B&Q (yes, I know, but it was a
Friday night...).

The 'B&Q' bulb (mfd. by GE) was significantly brighter than those supplied,
to the extent that I bought a couple more packs and replaced the lot. I'm
now happy with the resultant brightness.

But I'm wondering; is the increased brightness because the GE bulbs are
clear, and the originals were frosted, or is it because the originals are
cheapo no-name ones made in China and with a possibly dubious wattage or
efficiency? I'm interested to learn if there's such a difference...

There are a number of potential factors...

Halogens can be manufactured to be either more efficient
than conventional filament lamps by burning very slightly
hotter, or to have longer life. Nearly all the consumer
grade halogens are manufactured to have longer life (with
same efficiency as conventional filament lamps), because
it turns out domestic consumers won't pay the extra for a
halogen lamp if it only lasts same length of time as a
conventional filament lamp -- they never consider efficiency
at point of sale (well, anyone who does is unlikely to be
buying a halogen in the first place).

The frosting does lose light.

Different manufacturer's are likely to vary. (I once had
some very bad halogens sold under the Ring brand, which
behaved as though they just had a vacuum in them.)

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]