automotive headlights

[franksolich]

There occurred a most singular incident today, with the mechanic.

He was replacing a headlight on my motor vehicle (usually something I can do blindfolded, but in this case there's a whole lot of parts obstructing access to the headlight socket), and asked me to hand him the new bulb.

It was in a box; I opened the top of the box, and pulled it out.

The mechanic told me one is to open the box from the bottom, and pull it out from the bottom, so as to not touch the glass.

He said the glass has some sort of grease or oil or lubricant on it, so as to make the bulb last longer, and if one touches the glass, he rubs some of it off.

(a) If this is so, how come the box doesn't say "open at this end" on the bottom?

(b) If this is so, what function does the grease or whatever serve?

I imagine it's so, because the mechanic is a top-notch professional.

[rich_t]

Was it a halogen bulb?

[franksolich]

Was it a halogen bulb?

Now, that's stretching my knowledge of mechanics, sir.

It was some sort of bulb with a socket, and cost $7.02 after tax (I had purchased it; the mechanic just put it in).

[Carl]

It was a Halogen bulb,if you only have one for high and low beam the number should be a 9004 if I remember correctly.

They should never be touched by bare hands.
As it was explained to me when they first appeared in the 90s,the oils from your skin will stick to the glass of the bulb and create a hot spot which will cause it to prematurely fail.

Many now are in plastic in the box and/or have a black coating at the tip of the bulb to protect it.

[franksolich]

.....the oils from your skin will stick to the glass of the bulb and create a hot spot which will cause it to prematurely fail.

Aha.  So I misunderstood what he said.

Happens all the time when one's deaf.

I thought he said the oil was on the bulb, not the naturally occurring oil on the human skin.

[Carl]

Aha.  So I misunderstood what he said.

Happens all the time when one's deaf.

I thought he said the oil was on the bulb, not the naturally occurring oil on the human skin.

When they first came out the things were almost 20 bucks a piece.
Water getting into the reflector/lamp area of the light will ruin them in short order too.

[MrsSmith]

When they first came out the things were almost 20 bucks a piece.
Water getting into the reflector/lamp area of the light will ruin them in short order too.

They cost more than 10 times this for medical purposes. 

We are super careful not to touch them!