I have a bunch of new Rectangular (Hot Mirror) heat filters for an ORC lamp house. How can you tell which side goes toward the lamp? They have a tiny white sticker on one side so I assumed that side went toward the lamp. When I looked at the 2 that are in the lamp house now, the sticker is on the projector side.
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The "emulsion" side goes towards the lamp. Sometimes this is marked, often by a small etched mark.
But here's a trick I always use whenever I've taken a heat filter out and forgotten which side is which:
1) Lay the filter on a table. ( use a sheet of paper or a clean rag to prevent scratching)
2) Find something with a 'point' on it, like a sharp pencil, a toothpick, or a pin.
( I usually use one end of an un-bent paper clip)
3) Shine a bright light from a flashlight or your phone obliquely across the surface that's facing up.
4) GENTLY touch your 'point thing' to the surface of the filter, obviously being careful not to scratch it.
> If see a gap between your "pointer" and its' reflection, than that's the the 'glass' side of the filter.
> If your 'point' and its' reflection appear to touch each other, than that's the "filter' side
which should face towards the light source.
I learned this trick along time ago from an old theatrical lighting technician, and it works every time!
( and it's a fun thing to do if things get dull at your next projectionists party!) -
Thanks Jim. That worked perfectly. Turns out the existing glass was in backwards!!!Comment
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Richie, when you receive the new one it is marked on the handle , I marked the used one too for you!Comment
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