eerie green fluorescent lamps

[Jeff Jonas]

I salvaged some fluorescent lamps from photocopiers,
such as these 18 inch 15 watt
Kodak RB 897613
and smaller ones.

They all have a clear/clearer "window" the length of the tube
facing into the mechanism, and give an eerie green glow.

Why a window and what makes their light so eerie?
(great effect for halloween).

If this was ever discussed before, please give me some keywords
or links to find it. Thanks.

By the way, I sometimes find bulb collectors,
but are any into fluorescent lamps?
I still have a red and a gold 15 watt fluorescent lamp
which I am led to believe are now unobtainable.
If they're still sold, tell me where!

-- Jeffrey Jonas
jeffj@panix(dot)com
The original Dr. JCL and Mr .hide

 

[Andrew Gabriel]

I salvaged some fluorescent lamps from photocopiers,
such as these 18 inch 15 watt
Kodak RB 897613
and smaller ones.

They all have a clear/clearer "window" the length of the tube
facing into the mechanism, and give an eerie green glow.

Why a window and what makes their light so eerie?
(great effect for halloween).

These are Aperture tubes.

The phosphor in any tube has a higher luminance on the back side
which is lit by the UV from the discharge than on the front side
you see through the glass and emits the light from the tube.
An Aperture tube provides visibility of the brighter back of the
phosphor through the clear aperture where the phosphor
is missing. If you are mainly interested in light emitted in one
direction as the copiers were, then you can get a higher light
output in that direction by using an aperture tube and the light
from the back of the phosphor. The total light output is probably
less, but the loss is in other directions which you don't care
about.

Some aperture tubes also include reflectors, but the 18 inch 15
watt ones used in old Xerox copiers didn't. I think the reflectors
only appeared in more recent aperture tubes.

I can't answer questions on the colour. I too remember it being
an eerie green, which I assumed was optimised for the sensitivity
of the copier drum.

If this was ever discussed before, please give me some keywords
or links to find it. Thanks.

By the way, I sometimes find bulb collectors,
but are any into fluorescent lamps?
I still have a red and a gold 15 watt fluorescent lamp
which I am led to believe are now unobtainable.
If they're still sold, tell me where!

I'm pretty sure I've seen red tubes (that would simply require
just one of the phosphors used in standard white tubes). Gold
tubes were different - I'm not sure in what way, but I recall
the Thorn Lighting handbook saying their T12 gold tubes could
only be started on switchstart control gear, so the electrical
characteristics must have been different - maybe different gas
fill.

 

[Jeff Jonas]

me:
Andrew Gabriel:

These are Aperture tubes.
The phosphor in any tube has a higher luminance on the back side
which is lit by the UV from the discharge than on the front side ...

Thanks for the clear explaination and illuminating the topic (puns indended).

But does that mean I need to be cautious about UV
or does the glass absorb that?
Despite my interest in glass, it's hard for me to distinguish
otherwise identical clear tubes (germicidal lamps vs. regular lamps).
Wood's glass is easy to distinguish (blacklight lamps).
(the germicidal lamp is in an EPROM eraser).

Some aperture tubes also include reflectors, but the 18 inch 15
watt ones used in old Xerox copiers didn't.

Right you are! I have both.

I'm pretty sure I've seen red tubes (that would simply require
just one of the phosphors used in standard white tubes).

Ah, no wonder it's so dim but it's a very pure red light.
I guess I can't be so critical of the color-dipped helical CFL:
it's easier and gives more light anyway.

Gold tubes were different - I'm not sure in what way,
but I recall the Thorn Lighting handbook saying
their T12 gold tubes could only be started on switchstart control gear

I was just having that problem with the large aperture tubes:
won't light on my desk lamp, others were hard to start.
You're a mind reader!

Thanks again.
-- Jeff Jonas

 

[Don Klipstein]

I'm pretty sure I've seen red tubes (that would simply require
just one of the phosphors used in standard white tubes). Gold
tubes were different - I'm not sure in what way, but I recall
the Thorn Lighting handbook saying their T12 gold tubes could
only be started on switchstart control gear, so the electrical
characteristics must have been different - maybe different gas
fill.

I have seen "gold" fluorescent lamps. They appeared to me to be one of
the halophosphor whites (maybe "warm white"), with yellow glass or maybe a
yellow coating.

I have a Philips "SAG-100" catalog (North America) from 1999, and they
show a "gold sleeved" F40T12 rapid start lamp (F40/GO). In that wattage
and size, they also listed back then "Agro-Lite" and "Special Blue".
These may be F40T12 lamps compatible with both preheat and "rapid start"
(North America terminology), as many are.

"Agro Lite" and "Special Blue" were also listed for F20T12 preheat but
"gold" was not.

I do remember getting green and blue fluorescent lamps in the past,
even F15T8/B and F15T8/G preheat lamps. They were GE ones IIRC. Those I
got from Rose Electric on Germantown Avenue in Philadelphia around 1977.
Back then, I have seen red fluorescent lamps, appearing to me to be made
with red glass or having a red coating. A few years later, I got a GE
F20T12/B that I think I still have.

An impression I have is that F15T8 colored fluorescent lamps were
largely discontinued in the early 1980's, and after that colored linear
fluorescent lamps were only available in F20T12 preheat and F40T12
rapid-start-compatible.

Currently, GE's offerings of colored T8 lamps in North America appear to
me to be limited to 32 watt shatter-resistant red, green, blue, and a
"F32T8/B/65ECOCVG" mentioned as 6500 K. They still offer the F20T12/B
blue and F20T12/G green.

 

[TKM]

part:



I have seen "gold" fluorescent lamps. They appeared to me to be one of
the halophosphor whites (maybe "warm white"), with yellow glass or maybe a
yellow coating.

I have a Philips "SAG-100" catalog (North America) from 1999, and they
show a "gold sleeved" F40T12 rapid start lamp (F40/GO). In that wattage
and size, they also listed back then "Agro-Lite" and "Special Blue".
These may be F40T12 lamps compatible with both preheat and "rapid start"
(North America terminology), as many are.

"Agro Lite" and "Special Blue" were also listed for F20T12 preheat but
"gold" was not.

I do remember getting green and blue fluorescent lamps in the past,
even F15T8/B and F15T8/G preheat lamps. They were GE ones IIRC. Those I
got from Rose Electric on Germantown Avenue in Philadelphia around 1977.
Back then, I have seen red fluorescent lamps, appearing to me to be made
with red glass or having a red coating. A few years later, I got a GE
F20T12/B that I think I still have.

An impression I have is that F15T8 colored fluorescent lamps were
largely discontinued in the early 1980's, and after that colored linear
fluorescent lamps were only available in F20T12 preheat and F40T12
rapid-start-compatible.

Currently, GE's offerings of colored T8 lamps in North America appear to
me to be limited to 32 watt shatter-resistant red, green, blue, and a
"F32T8/B/65ECOCVG" mentioned as 6500 K. They still offer the F20T12/B
blue and F20T12/G green.

Most of the fluorescent lamps in colors have been delisted and are now rare
except, as Don says, red, green, blue and gold in F32T8 types. Some years
ago, if a color existed, it was sure to be listed as an "F40" since that
was, by far, the most widely-used fluorescent lamp type.

Red and gold fluorescent lamps appeared red and yellow respectively when
unlighted because the phosphors used were not able to produce pure colors
and so a filter coating was put onto the inside of the tube. Blue, green,
pink and several less widely used colors looked white when unlighted since
no filter was used. In decorative lighting applications (think amusement
parks) where many colored fluorescent lamps were being put into sockets and
taken out, it was hard to get the right color into the right socket because
either the fine print on the lamp label had to be read or the lamp had to be
lighted.

It's always been cheaper to use a white fluorescent lamp with an external
color sleeve or filter, but manufacturers found that customers liked the
convenience and simplicity of simply inserting a tube in a socket to get
colored light.

Terry McGowan