Film-Tech Forum ARCHIVE: Flaking Kneisley Mirrors

This is topic Flaking Kneisley Mirrors in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Bill Enos (Member # 440) on 12-30-2003, 01:17 AM:

The dichroic mirrors in both our Kneisley lamps are flaking the coating badly. They are 4000 watt lamps equipped with 3000 watt bulbs operating at 95 amps. They have 2 blowers, one blowing on each end of the bulb, exhaust from the lamps is adequate. History is this. They came from a drive-in that lasted only 3 1/2 seasons, hours were just over 1000 on each. The drive-in owner noted flaking the third season and bought a mirror at that time but didn't install it. They ran 4000 watts full out. Three months after we installed, one reflactor was so bad it was noticable less bright so we installed the new mirror. Both now shed so much that touching with anything is out of the question & cleaning with a blast from canned blow causes a cloud of metallic particles. Is there a problem with Kneisley reflectors?Would it be better to have them hot coated & use heat filters? Or can my dealer source them from other than Kneisley? Suggestions? The lamps were new in 1992.

Posted by Mark Gulbrandsen (Member # 72) on 12-30-2003, 08:00 AM:

Thats about the date that Kneisley had gotten a bad batch of reflectors fomr Optiform. They will either have to be replaced or sent to be re-done at Ultraflat. New mirrors are only a little more than having them re-done so I would choose new. Just about all manufacturers experienced this problem at least once or twice. Also be sure that your exhaust blowers are large enough and are operating properly for running that size lamp.
Mark @ CLACO