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From: (Don Wilkins)
Newsgroups: rec.crafts.metalworking
Subject: Re: Shop Lighting
Date: Mon, 26 Oct 1998 04:38:48 GMT

On Sun, 25 Oct 1998 15:06:20 -0800, "Martin H. Eastburn"
<> wrote:

>The 'pink' ones are standard looking bulbs - but have an improved
>color spectrum.  As I recall there is a pink color to the tube or

They added a different phosphor which emits in the red. Actually it is
a double coat with two phosphors. These were developed and marketed to
give a light which was closer to the spectrum of incandescent bulbs.

People didn't like the harsh look of the cool white lamps in the USA.
In Japan as well as some European countries there was less objection
to the cool white lamp in homes.

Both phosphors are white as is the aluminum oxide separating the
phosphors. I don't consider them pink but I can recognize them along
side a cool white tube.

>They are a little more, not much.  They were developed
>for office areas, but facilities tends to buy what they have to
>replace burnt out ones.

Actually they were hoping to make a big break through into the home
market but that market didn't grow as hoped.

Most industrial facilities do what is called "relamping". What they do
is remove and replace all of the fluorescent lamps at one shot instead
of replacing them as they burn out.

Apparently it is more economical to do that than to send an
electrician out to replace one lamp in an office and then get another
call to some other office at the other end of the building. In fact
there were usually an electrician plus a helper doing this.

Now they get an outside firm to come in an replace all of the lamps
AND in many states transport the old lamps to a recycling center to
recover the mercury. The recycler charges so much per lamp and that
cost goes back to the facility owner.

Some of the state laws are so restrictive that it is not feasible for
an industrial facility to do anything else. In most states the home
owner gets a free ride. I suspect that is because if there was a
charge for lamps from the home then it wouldn't take long for people
to figure out that it was cheaper to break them and stick them in the
garbage bag with the soup cans, etc. than to pay for recycling.

From: (Don Wilkins)
Newsgroups: rec.crafts.metalworking
Subject: Re: Light Bulbs (again)
Date: Thu, 26 Mar 1998 16:47:13 GMT

On Tue, 24 Mar 1998 08:32:14 -0500, Hoyt McKagen <>

>Mark Kinsler wrote:
>> Gonna see if I can make it into a fluorescent with some phosphor from the
>> insides of an old fluorescent tube.
>You know, of course, that the mercury in the lamp is poisonous? Be very
>careful, as a lot of it is also in the form of vapor.

As a matter of fact damn little is in the form of vapor. Currently the
charge of mercury metal is about 15 milligrams in a virgin lamp. You
will find only a few micrograms in the vapor state.
  _               _   _                  Für d' Flöh gibts a Pulver
 (_|   |   |_/o  | | | |  o              für d' Schuah gibts a Wix,
   |   |   |     | | | |      _  _    ,   für'n Durst gibts a Wasser
   |   |   |  |  |/  |/_) |  / |/ |  / \_  bloss fuer d' Dummheit gibts nix.
    \_/ \_/   |_/|__/| \_/|_/  |  |_/ \/

From: (Don Wilkins)
Newsgroups: rec.crafts.metalworking
Subject: Fluorescent ballast failure
Date: Sat, 21 Nov 1998 16:16:23 GMT

A while back someone asked about the failure mode in fluorescent
ballasts. A fellow retiree was the plant engineer for our ballast
manufacturing plant. Here is his answer including the reason for the
delay in posting.

	Just got back from a 12-day trip to the Sacramento-San
Francisco area, which we thoroughly enjoyed.
	In answer to your question about ballast failure, the
principal mode of failure is thermal degradation of the Class A
insulation system--- cellulosic layer insulation and polyester wire
enamel---of the coils. Accelerated life testing was employed to
establish an average life of twelve years, but continuing improvements
in materials and techniques in encapsulating the core-and-coil
assembly in a mixture of sand and asphalt kept pushing up the ballast

Early ballasts developed turn-turn or layer-layer shorts, which caused
overheating and the asphalt-sand encapsulant would leak
out of the case and onto the persian rugs below. To cope with this
problem, a single-shot thermal overload protector (consisting of a
fusible metal encapsulated in a wax compound) was developed to
permanently disconnect the ballast from the circuit before the
temperature got high enough to leak asphalt. Later on,
commercially-available resettable thermal overload protectors came
into widespread use. As of 1983, when I retired, many
of our popular fluorescent ballast designs were lasting 15-20 years.

He didn't say but as I recall the fusible metal was a small length of
wire made from one of the low melting metal alloys. Woods metal e.g.
Once it melted the ballast was dead and hopefully this happened before
the asphalt leaked onto the priceless rug.

From: (Don Wilkins)
Newsgroups: rec.crafts.metalworking
Subject: Re: Shop Lighting
Date: Tue, 27 Oct 1998 16:43:30 GMT

On Mon, 26 Oct 1998 17:30:41 -0500, James Wilkins <>

>Jens wrote:
>>  ....
>> Where in the tube is mercury used ?...
>> Jens
>Sometimes you can see a tiny drop of it in the bottom. There are a few
>milligrams of metallic mercury in there whose function is to evaporate
>and fill the otherwise evacuated tube with mercury vapor which ionizes
>around the starter filaments and supports the current down the tube. The
>resulting mercury plasma radiates short wave ultraviolet which excites
>the phosphors to re-emit the visible light.

Years ago the tubes contained up to 50 milligrams of mercury. Cost
saving and approaching regulations encouraged the manufacturers to
concentrate on reducing the amount of mercury in each tube. Most now
run around 25 milligrams but when you consider that annual
manufacturing is over 500 million tubes it ends up being a rather
large amount of mercury.

What the lamp manufacturers want is low enough mercury content so that
a crushed lamp will pass the EPA leach test. In other words landfill
instead of recycling. The recyclers want all lamps to be recycled no
matter what because of the total amount of mercury in play. Both have
vested financial interests but if lamps go to landfills the recyclers
go belly up.

The lamps contain an inert filling gas, typically argon, neon, or
krypton at a pressure very close to vacuum. Yes they call it a "fill"

The mercury in the vapor state is in the microgram quantities and it
is this mercury which is excited and emits UV light. Why do they put
25 milligrams of mercury in a lamp that is only using a few micrograms
in the vapor state? To get the 7 to 10,000 hours they suggest as
lifetime. Most lamps die due to mercury starvation i.e. they run until
all of the elemental mercury has combined with something in the lamp
to produce mercury compounds. That black stuff you see at the end of a
tube suggests that the elemental mercury is being removed.

From: (Don Wilkins)
Newsgroups: rec.crafts.metalworking
Subject: Re: Shop Lighting
Date: Thu, 29 Oct 1998 11:19:21 GMT

On 28 Oct 1998 18:40:55 GMT, "Randy O'Brian" <>

>Jens wrote in message <>...
>> (Don Wilkins) wrote:
>>> Most lamps die due to mercury starvation i.e. they run until
>>>all of the elemental mercury has combined with something in the lamp
>>>to produce mercury compounds. That black stuff you see at the end of a
>>>tube suggests that the elemental mercury is being removed.
>>Interesting - I always thought that there was a little filament at the
>>end that eventually evaporates just like in light bulbs ....
>There is and it does...........Randy.

Rarely. Most lamps die because of mercury starvation. No mercury vapor
no light. I consult for a lamp recycler and spent a career with a lamp
manufacturer. You can crush lamp after lamp and there is nothing wrong
with the filaments.

But if you have knowledge which is unknown to the lamp manufacturers
you can make a bundle by informing them that they can produce longer
life lamps by extending the filament life.

My prediction for your suggestion.... Circular file.

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