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NightLightingFX
09-07-2007, 07:27 PM
Have any of you ever experienced a white powdery build up on lamps and on the lamp side of a lens. I was doing some maintenance last night when I discovered a shadow that I projected on a wall didn't show-up. I messed around with it and couldn't figure it out. Today when it was light out and I wasn't rushed for time I opened up the fixture to find the lamp all covered with a white powdery film along with the lens. This was a 35 watt narrow beam with a linear lens (Some of you are wondering what are you doing with a linear lens and a narrow beam-I know what I am doing). Is the lamp getting too hot? The inside of the fixture doesn't show evidence of any kind of moisture decay or reminance. I have noticed it on some 50 watt lamps also. I don't like 50watt lamps but this project has a lot of ambient light I am competing with. It seems to me it is some kind of heat factor. I wonder if there is something I can do to prevent this? It is kind of a maintence hassle.
~Ned
www.nightlightinfx.com

Eden Lights
09-07-2007, 10:08 PM
Have any of you ever experienced a white powdery build up on lamps and on the lamp side of a lens. I was doing some maintenance last night when I discovered a shadow that I projected on a wall didn't show-up. I messed around with it and couldn't figure it out. Today when it was light out and I wasn't rushed for time I opened up the fixture to find the lamp all covered with a white powdery film along with the lens. This was a 35 watt narrow beam with a linear lens (Some of you are wondering what are you doing with a linear lens and a narrow beam-I know what I am doing). Is the lamp getting too hot? The inside of the fixture doesn't show evidence of any kind of moisture decay or reminance. I have noticed it on some 50 watt lamps also. I don't like 50watt lamps but this project has a lot of ambient light I am competing with. It seems to me it is some kind of heat factor. I wonder if there is something I can do to prevent this? It is kind of a maintence hassle.
~Ned
www.nightlightinfx.com

This has been discussed before, but I don't think we ever got a scientific answer. I have only seen it on one brand of lamp at the 35 and up wattage.

David Gretzmier
09-07-2007, 10:11 PM
I've seen this "frosted" effect before, but usually on lamps I'm replacing that I did not install. It seems to be more common on the higher wattages, but not always. try a different brand ad above states.

Go Halogen
09-08-2007, 12:50 AM
I have looked into this before. I have seen it happen to many brands of lamps. It is the mirror finish (reflective layer burning off). In most cases the mirror is nothing more than a few layers of metallic oxides or Dichroic coatings. Oxidation residue is what everyone is seeing and if you are near salt air.......you will see it more often. The "mirror" life expectancy is much shorter than the actual lamp life. How many of you know that most jobs ou there, older than 18 months, probably need new lamps? The lamp will keep burning but the reflective ability and lumin power has been greatly decreased.

I have been out to Ushio before. I learned all of this first hand. Guys get excited when they see their systems still burning after 3+ years. Check out the lamps. The mr-16 mirrors are gone and the reflectivity down by a huge percent. So in return, the lighting job is going to be less dramatic.

I always carry some old lamps with me to show customers why service is important.

Hope this helps.......

-Andy

ar-t
09-08-2007, 12:21 PM
That is pretty much the conclusion that I came to. I see it in fixtures with 35W and 50W bulbs. Almost never in 20W. Simply a matter of heat, boiling off the thin reflective coating.

Yes, the good brands last longer than the cheap ones (usually from China) the homeowners stick in. I also carry some old ones with me to 'splain to the customers why it is best to leave maintenance to the pros.

Chris J
09-08-2007, 05:41 PM
Because I live in coastal Florida, where there is high humidity and salt air, I see this frequently. Go Halogen seems to be spot on with his analogy as I can confirm that the mirrored reflectors will deteriorate quickly. This is one of the primary reasons that we recommend relamping annually for our customers. While the lamp may burn, the output of lumens and "punch" of crisp light rapidly decreases after 12-18 months in service.

NightLightingFX
09-08-2007, 09:24 PM
FYI, This was USHIO and it was only in the fixture for 6 mo. I live in a dry climate (East side of Washington State is Desert) but a lot of sprinklers where this fixture is. Hopefully I got a bad lamp. I am getting real close to just using "Color Constent." Thanks
~Ned
www.nightlightingfx.com

NightScenes
09-08-2007, 11:08 PM
Living in central Texas I have yet to have this problem with Ushio lamps. I did have it a long time ago when I was using lamps of lesser quality.

pete scalia
09-09-2007, 02:26 PM
buy GE, Ushio and the others are inferior. With GE constant you will not have this problem. You buy a $100 bullett and throw a $3 lamp in it and expect everything to be hunky dory? don't go cheap on bulbs it will burn ya baby!

Chris J
09-09-2007, 04:15 PM
I've used Ushio, Osram sylvania, Prisim, GE, and a few others... I haven't noticed that this climate discriminates against any particular brands. It seems it happens to me no matter which brand I use.