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  1. #1
    holmburgers's Avatar
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    Metering UV Exposures - Modern Actinometers?

    This could be hare-brained, but I just stumbled upon some products that measure your exposure to UV radiation.

    These are intended of course for beach goers avoiding sun burns, skin cancer, etc., but the potential for alternative printers is enticing!

    Here are a number of products:

    http://cgi.ebay.com/Oregon-Portable-...item2a0d4faa1a
    - (http://www.oregonscientific.co.uk/ul...B612-UV888.pdf)
    http://cgi.ebay.com/SUN-SMART-UV-EXP...item3a613515d5
    http://www.google.com/products/catal...d=0CGEQ8wIwBQ#
    http://www.google.com/products/catal...d=0CF0Q8wIwBA#

    Even something as simple as this: http://www.amazon.com/HQRP-Keychain-.../dp/B004XMH9FU

    The question is I guess, are they sensitive & accurate enough for reliable printing?
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  2. #2
    holmburgers's Avatar
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    http://www.solarmeter.com/

    These seem a bit more legit.
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  3. #3

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    Yeah...the ones in your first post all just seem to show UV Index, which is designed to predict skin damage from skin cancer. Not quite sure how it's computed or whether the 0-15 scale is log or linear or what.

    The second post (Solartech)...that seems like a possibility. Seems like the Model 5.0 might be the ideal one for alt-printers. Not sure if the "HP" variant (up to 1999 mW/cm^2) would be necessary. Honestly, I have no idea what the power output of a BL tube or a Nuarc lamp is.

    Thanks for the interesting links.

    --Greg

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    nhemann's Avatar
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    Interesting question so I did some reading (God save Wikipedia) BL tubes, which are mercury vapor lights, emit UV mostly (approx 90%) at 253.7 nm - which is below the measuring range for the 5.0. The Model 8.0 is just barely within range but it might not be so accurate that far to the left of the scale.

    However, unless I am mistaken, these units read an instantaneous value - as opposed to a totalized reading so you would still have to measure your time value as opposed to exposing for "units" of light.

    I couldn't find anything specific about a Nuarc but the seem to be just a different version of a Hg lamp so I assume a similar response.
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  5. #5

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    Quote Originally Posted by nhemann View Post
    Interesting question so I did some reading (God save Wikipedia) BL tubes, which are mercury vapor lights, emit UV mostly (approx 90%) at 253.7 nm...
    I'm afraid Wikipedia may have led you astray on this one. UV-C (germicidal) bulbs emit in that range. Typical bulbs used for alt-process (BL, BLB, actinic/aquarium/reptile, grow-light, etc.), typically emit in the 320-450nm range(UV-B, UV-A and visible blue light), depending on the exact bulb type, as do most metal-halide and mercury vapor arc discharge lamps.

    Glass absorbs much of the UV-B below 350nm...
    Dichromate (carbon, gum) has peak sensitivity around 370nm, I think.
    Platinum and Cyanotype have broader sensitivities, which can extend slightly above 400nm, I believe.

    Hope this helps...

    --Greg

  6. #6
    Ian Leake's Avatar
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    My vacuum frame came with a UV meter which was connected to a computer. The pair allowed the operator to dial in an unit-based exposure rather than a time-based one - the theory being that if your exposure is 500 'units' then this will allow for bulb warm-up and other variations of UV intensity. I don't actually use this because I replaced the original lamp with a more intense lightbox, but I'd like to explore these options at some stage.

  7. #7
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    Greg,
    Thats even more interesting - thanks for catching that and I stand humbly corrected - my confusion arose from the headings "black light" and "ultraviolet fluorescent lamps" (which I now understand to ba a tube with no phsophor coating at all) those interested can read the item here: http://en.wikipedia.org/wiki/Ultravi...Black_light.22 and here: http://en.wikipedia.org/wiki/File:Fl...s_labelled.gif

    Getting smart was apparently a two step process today!

    Greg, just out of curiosity, would the shorter wave length work or is it just out of the range to work in alt/plat processes? And again, thank you for correcting my error in research. :-)
    Last edited by nhemann; 06-02-2011 at 07:50 AM. Click to view previous post history.
    "There is no such thing as objective reality in a photograph"

    My flickr and (gasp!) dpug photos - take a look if you like.

  8. #8
    holmburgers's Avatar
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    The 5.0 and 5.7 do look ideal, to my untrained eye. These are pretty expensive though, at about $169.

    There are a number of $49 units too -> http://www.solarmeter.com/modelPUVM.html

    They're in the form of watches and are intended for monitoring sun exposure. Again though, could the values be useful to alt printers? Hmmm... very enticing, this is.
    If you are the big tree, we are the small axe

  9. #9

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    Quote Originally Posted by nhemann View Post
    ...would the shorter wave length work or is it just out of the range to work in alt/plat processes?
    I don't know if any of the common UV sensitive alt-processes (Pt/Pd, gum, carbon, cyano, kalli, etc.) have any sensitivity down deep in the UV-B or UV-C, because as a practical matter, it doesn't make a difference. Glass starts to absorb UV around 350nm (still in the UV-A region), and is essentially opaque to UV in the UV-B and UV-C regions. So unless you're going to get a contact printing frame that replaces the glass with fused quartz, it doesn't matter. UV-C is extremely dangerous to living tissue, and shouldn't be messed around with.

    --Greg

  10. #10
    holmburgers's Avatar
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    This begs the question, where is the hard data on the sensitivity of these processes?

    Does anybody have some fused quartz prisms to make some classic sensitivity curves?

    I've emailed the comapny and briefly described the needs of an alt printer and what they would suggest.

    Check this out... http://www.apug.org/forums/forum42/5...-uv-meter.html ...maybe someone should ask Nicholas about this, or perhaps he'll join the fray here and provide some insight.
    If you are the big tree, we are the small axe

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