Re: 5000 K bulbs for shop light

["Richard N. Moyer" <dickmoyer@earthlink.net>]

<x-flowed>Fluorescing phosphors are highly varied, and narrow banding phosphor 
are considerably more expensive than those which reemit broad bands. 
This is a general statement. Fluorescent lights have an intrinsic 
nature to emit high-end radiation - which the phosphors try to absorb 
and re emit at lower (visual) frequencies. What the electric arc 
wants to do and what the phosphors will do is highly dependent on the 
nature of these phosphors. And my experience is that precision tubes 
using precision phospers are going to cost you. Ditto for CRT 
displays. Also, the specialty narrow band tubes may be considerably 
darker because a good portion of the energy remains unconverted into 
light. Because these tubes go into a small niche market and no one 
else wants them for general illumination the cost is high. Wilhelm, 
in all his publications is very careful about spectral radiation's 
effect on both perceived color and absorption by media (printed 
papers, etc) and therefore ageing. A broadband fluorescent tube is 
not all the different from general purpose tubes. The 5000K tubes 
from Home Depot may be so broadband in spectral radiation that for 
all intents and purposes they don't differ from "normal" "cool white" 
tubes. The manufacturers of these tubes usually publish the spectral 
data, but if these come from off-shore, lick China, forget about 
getting the data, even if the brand is Sylvania (but made in China). 
Your light box was expensive because of special small bulbs.


>Someone else suggested this earlier, and I found that my local
>Home Depot carried at least two different brands of 5000K bulbs.
>I bought the Philips ones because they were what my light box
>used--but does anyone know why they appear (visually) to be a
>"colder" light than the standard cool white fluorescents I was
>using before?  I was expecting them to be quite a bit warmer,
>since the standard fluorescents are nominally something like
>6500K.
>
>Gary Hunt <glh@srv.net>
>
>At 02:48 PM 12/29/1999 EST, Fred Parsons  wrote:
>>I got some at Home Depot in Massachusetts.  GE makes them and they come in a
>>Chinese red card board cover with yellow print that says: "SUNSHINE full
>>spectrum light".  They come in both the 24 inch and 48 inch sizes.  Don't
>ask
>>store personnel for 5000K light bulbs, they told me they did not have any,
>or
>>they don't know what you are talking about.  But then I found them on my own.
>
>
>-
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Dick Moyer
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