Short lived halogen bulbs

[bernardgreen]

A few people have wondered why their halogen bulbs have a very short life before failing.

It may be related to the bulbs surface being contaminated after being handled with bare hands.

When changing a bulb hold the new bulb in clean tissue paper and do not touch it with bare fingers.

 

[jj4091]

Not being sarcastic Bernard, but do you have evidence to support this?I know the theories about oils from your fingers affecting the quartz, but have never had a problem with clean hands & suspected this was a bit of a myth.

 

[breezer]

i stand on the side on this one

it is a fact that the oil from your fingers will turn the quatz black as the high temperature of the quatz cooks the oil.

I have never seen it actually happen though (unless you dunk your hands in oil to prior)

I have a sealed lamp above the shower, the glass fell out the lamp is still working, despite being covered in a variety of steam, soap /water vapour, go figure.

 

[bernardgreen]

but do you have evidence to support this?I know the theories about oils from your fingers affecting the quartz,

No solid evidence. Only that the lamps I have changed using tissue seem to have lasted longer and when neighbours have started using tissue when changing their bulbs they have lasted longer.

Many years ago the high temperature quartz glass dinspection window of a furnace had to been replaced. Some one had touched the glass when setting up the experiment and when the furnace fired up a foggy area was seen to develop where the finger had touched the glass. The glass remained fogged after the furnace had cooled. The furnace was locked out from use until the window was replaced. A plain glass sheet added to prevent fingers touching the quartz window.

 

[Chri5]

Last time I bought some 240v Gu10 spots they came with a black sucker (a la toy arrow heads) to prevent the need to soil the lamp bulb with finger touches.

It was 1st spoken about years and years ago that handling them with bare hands would reduce the life hours

 

[bernardgreen]

Quoted from a paper on the use of glass in electronic equipment

The real, REAL, _REAL_ story with finger prints on tubes is that they
promote devitrification of the glass. Glass is called "vitreous" because
it has no crystalline structure. However, the major component
elements of glass are silicon and oxygen, and these elements would
just love to make a crystal called quartz. Fingerprints contain
impurities which give the silicon and oxygen a starting point to grow
quartz crystals. The heat makes the process go faster, so this problem
is more severe on power tubes. It is a problem because the quartz
crystals have intrinsic strength but are not attached firmly to the glass,
and do not contribute to the strength of the envelope. However, they
are made from the envelope and consume it as they grow. The glass
will eventually become thin enough that the envelope leaks or breaks.


This is a significant problem with the pure quartz tubes used for very
high temperature (in excess of 1000 degrees Centigrade) processing
of semiconductor devices, and goes much faster on vacuum tubes
because the glass envelope is quartz melted down with metallic
oxides to reduce the melting point and make it easier to work with.

 

[tim west]

could also be that the contamination is prone to causing hotspots that weaken the glass envelope.

 

[bernardgreen]

could also be that the contamination is prone to causing hotspots that weaken the glass envelope.

Alkali in human sweat causes crystals to start to grow in the glass. Once seeded the crystals continue to grow thus weakening the envelope of the bulb

 

[sm1thson]

siki it in the wiki bernard, there is a section especially for downlights that is somewhat incomplete.

 

[bernardgreen]

siki it in the wiki bernard, there is a section especially for downlights that is somewhat incomplete.

I just tried to under lamps but the page was non edit.