Beseler MCR 45 - Heat Absorbing Glass goes where?

Discussion in 'Darkroom Equipment' started by holmburgers, Mar 17, 2011.

  1. holmburgers

    holmburgers Member

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    So I just received a 6x6" piece of heat absorbing glass from a member. I've sent him a PM to ask but figured I'd ask out loud as well.

    Where exactly does it go? I took off the light head and managed to put it at the bottom of the upper bellows, right above the negative stage. It fits, but doesn't seem ideal since it doesn't really "clip" in or anything, just sits there.

    I'll look at the exploded view in the meantime.

    Thanks
     
  2. holmburgers

    holmburgers Member

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  3. Konical

    Konical Subscriber

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    Good Evening, Holmburgers,

    The HAG Beseler supplies is semi-circular at the rear and fits neatly into (onto?) the holder for VC printing filters. Normally, the HAG will rest atop any filter being used. It "just sits there" because it has nowhere to go when the filter drawer is closed. A square 6 x 6 piece of glass will not fit completely into the opening.

    Konical
     
  4. Photo Engineer

    Photo Engineer Subscriber

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    In practice, the HA can go anywhere above the negative, but never below. As long as it fits snugly with no light leaks around the edges it will do the job. In the strictest terms, it is used mainly to protect the negative or slide from heat more than anything else. The UV absorber may go above or below the negative or slide, but is best placed above the slide.

    These two items are there to protect the original from excessive harmful radiation as well as to provide trimming action for the light.

    PE
     
  5. holmburgers

    holmburgers Member

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    Thanks guys. Well indeed mine is square, so I'm afraid it's not an ideal fit. The funny thing is (which I haven't checked just yet... I had some St. Patrick's day celebrating to do...) I might have HAG in there already, seeing as I didn't know where it was supposed to go anyways.

    Out of curiosity, what is in the glass that makes it heat absorbing? Some kind of IR absorber? I'm surprised that the huge masses of glass that are the the condensers don't do the trick.
     
  6. Ian C

    Ian C Member

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    Heat passes through non-HA glass without being absorbed.

    HA glass is an alloy of glass that contains an iron compound that absorbs heat from the light passing through.
     
  7. Photo Engineer

    Photo Engineer Subscriber

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    HAG is a faint green or cyan in color.

    PE
     
  8. holmburgers

    holmburgers Member

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    Muy interesante