UV light source for alt. process lab source?

[eric_mortensen3]

I am getting started in alternative printing processes that require Uv

light. As a biochemist that works in a biological research lab, I have

access to light boxes that emit 280nm or 260nm UV for visualization of

DNA. The dye Ethidium Bromide (which is a powerfull carcinogen) is

used by labs to stain DNA and to visualize it under these light

sources. Contact with this short length UV is harmfull to the eyes and

skin if not properly shielded, but these UV light boxes have protective

covers to avoid exposure. My question is, has anyone tried these sorts

of light boxes for exposing prints? It seems to me that these would be

very usefull for alternative processes that require UV, and are

available online from lab surplus auctions. Other than the fact that

you would want to clean these up with gloves on to get rid of any

Ethidium Bromide, that they could be very usefull.

Eric Mortensen

[jorge_gasteazoro4]

Yes one of these lights would be perfect for pt/pd. The only two things I would look for, would be to see if you get an even exposure across the entire area you wish to expose. If I remember correctly gel electrophoreses lamps are kind of small, but then it has been many years since I have been on a lab! I have a NuArc plate burner and I beleive the UV range is 300 to 500 nm, so your lamps would be even better. The other one would be the kind of voltage and amps required for the lamp. My plate burner requires a 20 amp breaker on a 120 volt line, so I had to make sure the wiring in my house would be good enough to handle this load. Since I have never seen the instrument you mention maybe this is not required but you never know!

[kelly_flanigan1]

We have a "adalux"? lamp above our 32x45" vacuum frame that is used for contact prints. It has a 230 volt input; and has a timed shutter that open and closes below the bulb housing. It puts alot of UV light; plus visible too. Our several blueline machines put out alot of UV; they are 7000,6000, and 5000 watts.<br>use some UV resistant glasses to protect your eyes; UV can be dangerous.

[david_willis]

I've used the UV light box in my lab to do van Dyke brown prints. It worked great. Ours is a variable intensity Fisher model. It's got the safety shield you mention and also a piece of UV transparent plastic that sits on top to keep the light box from getting scratched. I moved that out of the way, set up the print, lowered the safety shield, and went back to my experiment. Fifteen minutes later, the print was done, and I fixed and washed it.

 

The box we have would work fine for 4x5 or 5x7 prints, but it's too small for 8x10 prints.

[don__]

Eric,

 

The range of wave lengths that you specify are not the optimum part of the UV spectrum desired for alternative process printing. You may wish to refer to these two web articles for more information:

 

http://unblinkingeye.com/Articles/Light/light.html. This link has an excellent article by Sandy King which discusses differnt types of UV lighting and their applicability and efficiency with different alt. processes.

 

http://unblinkingeye.com/Articles/UVBox/uvbox.html

 

The second link shows a homemade unit similar to one I made several years ago. If you choose to DIY and build your own I would recommend fabrication out of sheet metal to reduce weight dramatically.

 

Whatever you do I would recommend spending the time getting a capable light source. It will save you time and frustration while learning alterantive photography processes.

 

Good luck,

 

Don Bryant

[pete_caluori]

Greetings,

 

I can only answer your question from research I've done. Don's answer is in line with that research. In addition to Sandy King's article, Dick Arentz in his book Platinum & Pallidium Printing says the same thing. The most useful region is from 320 to 400nm, which leaves your light source outside that region. It will probably work, but your exposures will be much longer. All of my exposures have been using the Sun as my light source, but I have a NuArc on its way.

 

Regards, Pete

[eric_mortensen3]

Thanks for the info and feedback. Since short wave length Uv light is actually more intense than longer, Im guessing the esposures will be shorter than what is recommeded. I will give it a go and let others know how it went.

Eric

[linas_kudzma]

Eric,

 

The short wavelength UV light is not the correct wavelength to convert ferric oxalate to ferrous oxalate. Regardless of the intensity, if these lamps don't also put out considerable longer wave UV the exposures will likely be longer than sunlight, BL fluorescent tubes (which I use) or metal halide lamps commonly used by Pd/Pt printers. If they emit ONLY the short wavelenghts it's possible they may not work at all. Do your own tests.

[jorge_gasteazoro4]

I disagree with Linas, if you read Arentz's book you will see on page 12 a diagram of the UV spectrum and the range where actinic coversion of pt/pd salts occur, this mainly happens at in the 250 to 290 range. Also on the same book on page 13 he writes:<p>

" NuArc has come out with a metal halide model 26-1ks. Analysis of the published data indicates that it will work in the 200 to 400 nm range, and most likely adequate for conversion of Pt/Pd salts, perhaps requiring less exposure time."<p>

 

So yes the lamp <b>will</b> work and your times will probably be shorter.

[linas_kudzma1]

Jorge,

 

I'll have to look at the Arentz book; perhaps he found a good reference to this info in the chemical literature. In any case, I believe that most glass blocks nearly 100% of UV shorter than 280-300nm. If this is correct, the really shortwave UV is useless in a glass faced print frame. I know that laboratory "glassware" that needs transmision of shortwave UV is quartz.

 

A test with the shortwave lights is the only way to be sure.

[jorge_gasteazoro4]

Linas, <p>

 

The lamp will work to oxidize the oxalate, so the chemical reaction will proceed, which is what you stated on your previos post. As to the glass you are correct regular silica glass will block the UV, but that is another matter, no?<p>

 

I dont know much about this lamp to say wether it has a quartz glass or not, but in a previous post on this thread someone used one to make Van Dyke brown prints, so I am guessing it would not be a stretch to use it for pt/pd

[linas_kudzma1]

Jorge,

 

OK. Let�s assume that Arentz�s data is accurate. However, it remains that even if shortwave UV will reduce ferric (Fe+3) oxalate to ferrous (Fe+2), it is still problematical to use due to the print frame glass issue as well as the much greater eye/skin hazard as compared to longer wave UV sources. It seems to me that UV sources emitting mostly shortwave just aren't the best idea for Alt printing. I�m not trying to be unpleasantly argumentative, sorry if I come off that way.

[jorge_gasteazoro4]

Linas:

Not at all, is good to discuss this, the devil is in the details no?

Ok, first you are correct I should have said reduced not oxidize, hard to keep track of the electrons without coffe...:-).

Now, it seems to me you are as much in the dark about these units as I am. From what Eric described these units have a protective glass so the viewer is not exposed, so I dont think the greater risk you mention is a factor, lets remember gel electrophoreses has been around for a long time and if these units were unsafe I am sure OSHA would have at least curtailed their use in the lab. Now, do you want to get one at home? I would not! they are expensive, small and not any better than what you could have made at home with a few ballast, wire and wood. As a matter of fact my first printing source was a box I made before I got the NuArc.<p>

The glass issue I guess would depend on the thickness of the glass, normaly printing frames have a 2 mm glass, rather thin in my opinion. If this thickness does stop <b>all</b> the UV source then you are correct, it would not work. I dont think this is the case though. Some would pass through and being of such high energy it would reduce the Iron. Anyway, like I said before apparently it has been tried with Van Dyke brown and it worked, I dont see why it should not work on pt/pd. I guess we should wait and see what Eric reports, if he does...:-))

Take care Linas.

[eric_mortensen3]

The units I am referring to have a plexi-glass cover that comes down to shield the viewer from being exposed, however the lamps are exposed underneath this so as to allow the uv to penetrate and illuminate the agarose gel. Im assuming that unless the glass in the contact printer frame blocks the usefull UV (which I assume it doesn't since people use these to make platinum prints etc) that this would work. Im going to "borrow" one soon and I'll let you guys know how it works out. Eric