MH bulbs, how can you tell they have been used

[ramone58]

I have a friend who thinks mogul bulbs he purchased new from a LFS might have been used. How can you tell, or can you?

[James77]

If the arc tube is darkened on the ends is a sign that they have most likely been fired once. Some bulbs, usually with electronic ballasts, will show no discoloration at all. Also, some bulbs come with some coloring from the materials used for it.

Why does he think they were used?

[grigsy]

It's hard to say. Often times when I get a bulb it has a burn mark on it. Usually companies will test the bulb prior to shipping. The gas in the inner arc tube will expand then adhere to the chamber holding it. That leaves the spot on it.

[sedor]

My question would be why he thinks they are used. If he has an issue maybe he could take the bulbs back to the LFS and they could at least compare another set to prove they are in fact new.

[spamreefnew]

i know when my bulbs start getting old they get black arc tubes,,and almost every new bulb has one black spot from testing