If you look very closely, you will see very small accumulations of what appears to be fine white powder on the inside surface of my Cibie H-4s. It does not seem to adversely affect the lighting characteristics, however. If you tap gently on the lense surface, it sometimes drops to the bottom of the h/l shell. Any ideas?

Probably dust or remains from a broken light bulb. I washed the inside of the Bosch H-4s I have with some warm soapy water and then placed it in the sun to dry, they came out pretty clean and it didn't affect the reflective finish.

Smuggler...

Busted!

I did the same thing with the headlamps for an '86 Audi that I had. The fixtures had a dust haze accumulation on the inside. Took the fixture out and washed with warm soapy water. Rinsed clean and then dried it with a hair dryer pointed into a 1 inch diameter plastic hose to direct the warm air into the fixture.

Spoke

Fairy dust.

I've seen it in light bulbs before but I haven't the faintest idea.

Mihai,
A bulb has never broken in the h/l as yet. This substance is white. I've never seen "dust" white like this.

Eric,
I just knew someone would insinuate some illegal activity associated with this post.

snort it. you may get lucky. but you may die too.

interesting choice

wash em

Wash with soapy water,

Rinse well, final rinse with distilled,

Pour in a bottle of rubing alcohol- as high a proof as you can find, slosh around to absorb water, pour out, place in sun to evaporate alcohol.....

and.... no spots!!

(old telscope optics cleaning trick)

Ken