Incandescent Filiment Support Prongs?

C. Nick Kruzer wrote: >

. You could try asking at sci.engr.lighting It has some very smart people.

From an old thread there, a couple opinions (not certain) were iron or nickel-plated iron molybdenum

Might make a difference between center supports (on some lamps) and end supports.

Incandescent bulbs may be hazardous as well: Animal studies of tungsten shrapnel show that it is a very powerful carcinogen. I don't know how tungsten dust (which I assume must be inside the envelope after the filament burns out) would behave in the lungs, but I suspect the answer would be "not good".

This may not be an environmental hazard like mercury in landfills, but on a personal experimenter basis it may be much worse. (My understanding is that mercury is a problem mostly in organically active forms like methyl mercury, not as a raw element.)

Best regards,

Bob Masta DAQARTA v4.00 Data AcQuisition And Real-Time Analysis

All sorts of phosphors on the inside of the glass as well.

Considering the original quantity of tungsten, and distribution of 'shrapnel', you have a low probability of ingest (stomach/lungs) enough tungsten to be more than a minor irritant. From recollection it is difficult to absorb tungsten through skin contact.

In this case the poster referes to GOOD bulbs not burnt out ones, and trying not to smash the glass. So the shrapnel is minimised.

More likely to have dust problems with types of bulbs that are internally coated with phospors.

As a raw element at room temperature it will form a gaseoues mercury vapour and some Mercury Oxide that can easily be breathed in, often seen looking like a heat haze above raw mercury. What quantities you should worry about I have no idea. Any heating of mercury is always suggest to be done in VERY well ventilated areas.

Methylmercury is usually created by bacterias reacting with mercury, there are many different types of bacteria on and in our bodies.

Heating Mercury Oxide to a fairly high temperature decomposes the solid form back to mercury and oxygen (see Preistley's experiments often hailed as the discovery of oxygen). This is one method used to refine Mercury from some types of ore.

Mercury can be absorbed through the skin

To think this element was used for cosmetic and HEALTH giving properties for thousand of years and gave rise to the expression

"As mad as a hatter"

Lots of lighthouses use a bed of mercury for the load bearing of the rotating lenses for the lights. These places are usually well ventilated!

Nearly all fluorescents have phospor coatings on the inside of the tubes also very nasty in dust form.

As I recall, the animal studies used tiny particles of tungsten. The tumors were formed directly at the point of skin contact... no absorption needed. (I believe they "implanted" the particles through tiny incisions to hold them just under the skin surface.) But the alarming thing was that the particles were pretty much 100% effective at causing tumors... not like "increases the risk of", as we see for things like smoking or radon.

Best regards,

Bob Masta DAQARTA v4.00 Data AcQuisition And Real-Time Analysis

Yes, usually. The old standard way to secure wires in glass, or to feed wires through a glass bulb, is to use Kovar wire (see ) and a selected type of glass for the bulb base assembly (though the bulb fused to the base might be a different material).