Fluorescent bulbs in living areas.

[RobertL]

In the bigger lamps there is a choice over the spectrum of the light emitted - its' indicated by the "color temperture" .

[ARWadsworth]

dennis knows nothing about anything but it does not stop him commenting about most subjects.

[ARWadsworth]

That will by why he posted on the "Scratches in a glossy worktop" thread then.

I'll get my coat.

[The Natural Philosopher]

fingertips are the best sensors for surface smoothness..ask any Romeo.

[Andrew Gabriel]

So did my parents - still there. I have replacement tubes/ballasts waiting to go in when the room is redecorated.

but still far short of final light output, and the run-up time for a long T12 tube is almost half an hour (so people don't notice).

With T8 and T5 tubes, it's more noticable. Unfortunately, it's a trade-off for increased efficiency and lower mercury dosing.

[Andrew Gabriel]

They were the bee's knees at the time, particularly the circular tube ballasted with a regular filament lamp in the middle, all behind a glass diffuser.

Then there was the Milk Bar fittings, with the 3 different sized circular tubes nested inside each other.

The original T9 circular tubes will probably vanish over the next few years. There are now T5 ones now which meet future efficiency requirements, but not compaitible.

[John Rumm]

Your choice of words there may be slightly confusing since its conflating two separate things. The colour temperature will dictate the overall perceived tone or "warmth" of the light (with counter intuitively, lower colour temperatures appearing warmer, and higher temperatures appearing cooler or bluer), but the spectrum emitted is a more complex affair than just the overall perceived tone or the "whiteness". Its possible to create the same colour temperature as a incandescent lamp quite easily with a CFL, its very much harder to create the same spectrum without noticeable peaks and gaps in it. Hence looking at the bulb, they can appear very similar, however the light reflected from a range of coloured surfaces can appear very different.

[David Paste]

I wandered around the house last night with a CD and compared the spectrum I could see on the back of it under different lamps. The best was the one incandescent lamp I have, in the toilet - nice continuous spectrum, followed by the linear fluorescent tubes in the kitchen. The CFLs all had gaps in the spectrum, which actually looked quite pretty on the CD, but clearly lends to my dissatisfaction with the lamp itself.

Thanks to all for the suggestions and views given.

[Andrew Gabriel]

My guess is that the linear fluorescent you checked is a halophosphate tube (which are being phased out because of poor efficiency).

Your filament lamp will have a CRI (Colour Rendering Index) of almost 100. Tri-phosphor tubes achieve CRI in the 80's. Multi/poly phosphor tubes with CRI of 90 or more will also have more infill phosphors, but they are harder to find and expensive.

Most bog-standard halophosphate tubes had CRI in the 70's, but they were available in everything from 50 to 90, although the high CRI ones were rather inefficient. The low CRI in these cases was more often due to lack of balance across the whole visible spectrum, rather than discrite line sources.

Tube colours and CRI are usually given by a 3-digit code such as 830, which means CRI in the 80's, and colour is 3000K, or 940, which means CRI in the 90's, and colour is 4000K.

CFLs are normally 827 (CRI in the 80's, and colour is 2700K, which is designed to be same as the filament lamp they are replacing, and for mixing with other filament lamps).

2700K-3000K is warm white (filament lamps are 2700K). 3500K-4000K is white 4000K-5500K is cool white 5500K-6500K is (misleadingly referred to as) daylight or full spectrum (which doesn't mean full spectrum at all - it's a marketing term).

Each colour temperature has a range of lux levels at which it looks right (Kruithof curve). So 5500K will look right at midday sunlight levels (e.g. your ceiling plastered in fluorescent fittings), but it will look blue with one fitting generating twilight lighting levels normally used indoors.

For a living room, you probably want a lighting level were 2700K looks about right. Kitchens generally need higher lighting levels where 3500K would be more reasonable. Supplemental lighting in an office during daylight is going to use white or cool white tubes.

[PeterC]

I must try that. T'other day I wanted to get a photo of something under a CFL - the initial view on the LCD was a horrible yellowish colour then, after a couple of seconds the camera corrected it to somewhere near normality. Still not 100% but OK for the purpose.

[David Paste]

Ah yes! "White Balance"!

[The Natural Philosopher]

juts as easily achieved with Photo* post processing...

[David Paste]

Thanks for that. I went rooting around in *The Drawer* and found an IKEA branded CFL with 946 printed on the bottom of the pack. I am sure this won't be what I want it to be. I'll see what the back of the CD has to say after the sun has disappeared.

Looking at the rest of the CFLs (accumulated over the past few years by many people) in *The Drawer*, it seems that colour codes / information have only recently been printed on the packages.

[Maria]

I have a warm white tube in the kitchen which is not too bad - it's not clinical at all, but does yellow colours somewhat. I've had CFL's in my house for several years now, and had no idea just how bad they were until I bought a second hand table lamp a few days ago, which had a 40w incandescent bulb in it. It blasts light out! I always thought 40w bulbs were quite weak when I only ever used traditional bulbs, but now there is a gorgeous warm glow in the room. The light seems to be thrown out further, but maybe it's just me.

[DerbyBoy]

They were the bee's knees at the time, particularly the circular tube ballasted with a regular filament lamp in the middle, all behind a glass diffuser.

Then there was the Milk Bar fittings, with the 3 different sized circular tubes nested inside each other.

The original T9 circular tubes will probably vanish over the next few years. There are now T5 ones now which meet future efficiency requirements, but not compaitible.

[David Paste]

Well, the more I read in to lighting, the more these CFLs seem like a shoddy idea - they have just been marketed as replacements, but I found some webpage which gave recommended light levels for a given area, and so I borrowed a light meter and found that the 'direct replacement' CFL throws out around one-third the recommended light. So I bodged a few more bulbs and it certainly improved things a little, but I do think that there should have been more information given to people about the lumen levels. The CFL I have apparently puts out 550, which I suppose will decrease over time, and the recommended level for the room I was testing works out to a little under 1500. Of course, I have not tested the light given off by a traditional incandescent lamp, but I will do this evening...

[PeterC]

Toolstation has a "warm white" tube in the dogalogue - colour temp. 8300K! That's warm!

[Andrew Gabriel]

I have a 20000K 250W metal halide lamp. I used it to light up the back garden one year after a heavy snowfall, and the effect was quite mind blowing. It looked like the garden was being lit by a nuclear reactor.