Technique? Final finish on Aperture Plates.

[Ryan Gallagher]

A 1960's projection manual I have, as well as some of the JJ manuals gave this advice when filing plates:

'"after the plates have been filed to the proper requirements it is suggested that a 30° bevel be filed around
the aperture opening with the sharp edge towards the film. . .After filing it may also be desirable to paint
the bright surfaces with a dull black enamel to stop all reflections. "

Both of those sources only seem to mention painting around the aperture opening in relation to 70mm, but
I've worked in several 35mm screening rooms & theaters that had the aperture opening trimmed with flat black
paint. I think I actually have several 35mm plates in my collection that are made from some sort of black metal.

Some of ours are black in coating or patina, but once you file them still shiny brass under there.

I knew I had read that taper thought somewhere, thanks. Though I still think doing it after sizing is a bit risky unless you’ve got a jewelers loop or something. Painting them is an interesting thought. I’ll wait till my skills have me producing perfect plates before I consider such fancies. Lots of our existing ones need redoing, so practice makes perfect?

[Mark Gulbrandsen]

Some of ours are black in coating or patina, but once you file them still shiny brass under there.

I knew I had read that taper thought somewhere, thanks. Though I still think doing it after sizing is a bit risky unless you’ve got a jewelers loop or something. Painting them is an interesting thought. I’ll wait till my skills have me producing perfect plates before I consider such fancies. Lots of our existing ones need redoing, so practice makes perfect?

That's not paint, that's just a black oxide coating on the brass. Not sure why they bothered to do that. Definitely absorbs heat. Doing the final cut at an angle is a must, but may take some practice, and you can get that practice before you have it fully filed to the size you need, or practicing on old plates... I've never painted any. the paint is just gonna just burn off the plate in the heat anyway