Arctube can't be seen through the pearl finish of old chinese Osram NAV-E lamps? « on: June 15, 2017, 09:13:02 AM » Author: dor123
I've noticed strange thing that occurs to the pearl finish of the chinese Osram NAV(SON)-E 150W and 250W, when they are old: When they are new, the arctube can be seen clearly through the pearl finish: http://www.lighting-gallery.net/gallery/displayimage.php?pos=-121988 But when old, the arctube can't be seen correctly through the pearl finish: http://www.lighting-gallery.net/gallery/displayimage.php?pos=-134470 This can be clearly noticed when the lamps cycle during run-up before returning to normal operation: http://www.lighting-gallery.net/gallery/displayimage.php?pos=-134694 Why this is happening?
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I"m don't speak English well, and rely on online translating to write in this site.
Please forgive me if my choice of my words looks like offensive, while that isn't my intention.

I only working with the international date format (dd.mm.yyyy).

I lives in Israel, which is a 220-240V, 50hz country.

	Re: Arctube can't be seen through the pearl finish of old chinese Osram NAV-E lamps? « Reply #3 on: July 10, 2017, 01:22:04 AM » Author: dor123
Quote from: James on July 09, 2017, 05:13:06 PM I have never noticed this phenomenon before, are you sure it is not related to the production date of the lamps?  Traditionally they used either calcium pyrophosphate or alumina powders for the coating, which has excellent light diffusion characteristics.  However it also absorbs nearly 10% of the light output.  More recently manufacturers have shifted to fumed silica coatings with much smaller particles and a very tight particle size distribution.  Such coatings have much better light transmission but less diffusion, and the filament or discharge tube can be seen more easily. I this video , there is an embedded picture of a chinese Osram NAV(SON)-E 250W, showing how the arctube image looks through the coating at EOL, when they are operaing. These lamps aren't really frosted, but have a coating that causes them to look like that.
		Logged

I"m don't speak English well, and rely on online translating to write in this site.
Please forgive me if my choice of my words looks like offensive, while that isn't my intention.

I only working with the international date format (dd.mm.yyyy).

I lives in Israel, which is a 220-240V, 50hz country.