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Thread: Uva alt print box

  1. #1
    Tin Can's Avatar
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    Uva alt print box

    Barina UVA Black Light Lamps as sold on Amazon

    I just got mine cobbled together today. Lamps on, vacuum stage with pump and timer. I do need to tidy up a few details, like a door for the front, a prop for the top.

    I ordered mine March 16, 2020 before Tim posted his update. April 05, 2020 Darkroom Diary: LED Update To My UV Printer For Platinum Prints

    Below is a Pro Screen Burner using the same lamps and specs

    The rest are safety concerns. Read them!

    https://anatol.com/pre-press/aurora-...exposure-unit/

    https://www.skincancer.org/risk-factors/uv-radiation/

    https://www.seelife.net/eye-care-ser...ue-light-eyes/

    https://phc.amedd.army.mil/PHC%20Res...4-014-0815.pdf

    UVA 1 by TIN CAN COLLEGE, on Flickr

    UVA 3 by TIN CAN COLLEGE, on Flickr

    UVA 2 by TIN CAN COLLEGE, on Flickr

    UVA 4 by TIN CAN COLLEGE, on Flickr
    where is the monolith

  2. #2
    Gary Beasley's Avatar
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    Re: Uva alt print box

    You did good. Did you use the jumpers supplied with them to link several bars together So you have fewer plugs to deal with? I did mine in sets of two so I had four plugs run into a power strip.
    Attached Thumbnails Attached Thumbnails C2383BB2-8DA5-466B-9172-C5145B5A1F2F.jpeg  

  3. #3
    Tin Can's Avatar
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    Re: Uva alt print box

    Yes I did, Barina specs show we can daisy chain 10 of their lamps

    I used all 12 I bought with 2 chains yielding 2 120 VAC household plugs using a doubler to join them at the timer

    Some old timers don't work well on some LED, but this 12 X 9 watt = 108 watt load works well on that timer

    I also bought a dozen Barina LED white light 3 years ago using them in my shed. 1 failed fairly quickly but 10 work at any temp, from 0 F to over 130 F which broke my thermometer. I had a spare in hand.

    I will buy more from Barina asap as I now fear shortages
    Last edited by Tin Can; 11-Jul-2020 at 17:30.
    where is the monolith

  4. #4

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    Re: Uva alt print box

    On the matter of safety, I've seen high power UV units wired so that you have to be out of the room & the door locked or (on smaller units like yours) there are baffles with microswitches on them that have to be in place before the UV lights will even switch on.

  5. #5
    Gary Beasley's Avatar
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    Re: Uva alt print box

    I doubt the Barrina lights emit the harmful uv rays as they are designed for use in a room with people in it. It still makes sense to not spend time staring directly at the lights. My setup has the lights on the underside of a drop down support. I do need to track down some blackout material to make a skirt around the sides of it to limit the overspill.

  6. #6

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    Re: Uva alt print box

    Quote Originally Posted by interneg View Post
    On the matter of safety, I've seen high power UV units wired so that you have to be out of the room & the door locked or (on smaller units like yours) there are baffles with microswitches on them that have to be in place before the UV lights will even switch on.
    This makes sense particularly for units that emit a broad spectrum of (UV) light such as old-fashioned gas discharge bulb plate burners. However, for UV-A tubes and leds, the safety issues are of significantly lesser concern. While it's still not a good idea to stare into such sources for any extended period of time, exposing a couple of prints per day won't expose you to more UV than going out for a one-hour walk on a sunny day (in fact, it's likely to be substantially less!) Risks such as skin cancer when working with pure UV-A sources are sometimes overstated by the overly anxious. Of course, it's always a good idea to err on the side of safety, but there's no need for grave concern in this particular use case.

    The primary safety concern with UV-A is to keep in mind that if you use a led or tube UV-A source, only a fraction of the light emitted is in the visual spectrum. This means that the eye (particularly the pupil) 'thinks' there's a lot less light than there really is. This means that you can suffer from irritation/headache if you work in a fairly dim room (i.e. normal artificial room lighting levels) with your UV exposure unit on. To prevent this, either apply proper shielding (e.g. skirts on your exposure unit) or wear UV blocking glasses. Perspex safety glasses already to a pretty good job at blocking out the majority of the UV spectrum as plastics tend to not pass shorter wavelengths, and of course you can always resort to a decent set of UV-blocking sunglasses. While the risk of actual damage to the tissues of the eye (cf. 'Klieg eyes') is very limited, it can be a good idea to minimize any possible discomfort (just as you don't want to go out skiing without sunglasses, although this is actually more risky to the eyes than a day-long printing session).

    Again, the above nuances to the safety issue very explicitly do NOT apply to light sources that also emit significant amounts of energy in the UV-B or even UV-C spectrum (e.g. germicidal lamps). Those are outright dangerous and in my opinion do not have a place in a contemporary darkroom. Since all alt. processes are mostly sensitive to the UV-A spectrum (particularly the bit between 350nm and 390nm), or at least they perform very well at those wavelengths, there's absolutely no reason at all to incur the safety issues and inefficiency of smaller wavelengths.

  7. #7
    Tin Can's Avatar
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    Re: Uva alt print box

    I do plan to install a light blocking door on my unit, ASAP

    Soon I will test Sun VS my iteration with a UV meter, that peaks in UVA before engaging in any printing

    When young in the 50's and 60's I did ski without sunglasses

    I found I preferred night skiing, perhaps too late

    Time is of the essence for everyone now
    where is the monolith

  8. #8

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    Re: Uva alt print box

    These units appear to operate within the very narrow range of 395-400. Since this is not within ideal range for alt prints, does anyone have printing times for salt, VDB, casein, kallitype, Pd, Pt, or other processes?
    How do the times compare with fluorescents?

  9. #9
    Gary Beasley's Avatar
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    Re: Uva alt print box

    Mine are spaced 3.25” apart, 7” above the glass, getting 9-10 minutes exposure time with pictorico ultra digital negative with ultrachrome inks.

  10. #10
    Tin Can's Avatar
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    Re: Uva alt print box

    My LED are untested yet, but I think the same as Gary B and exactly what Tim Layton is using.

    My spacing 1" apart and 2" above NuArc glass with plenty of room inside the NuArc for 16X20 + 2" if needed

    If my prints are too quick I will take out the NuArc vacuum frame and test with normal contact print frames

    I can also remove any LED in minutes
    where is the monolith

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