The final two elements of the new UV Solar Printer are the Fluorescent tubes and reflective Mylar that will be behind said tubes, both arrived yesterday, within five minutes of each other. Both were only found online after extensive searches, but I must say it was worth the wait as the outcome will be most beneficial to the printing.
Tomorrow is scheduled for transport of the printer & parts to the PJ's darkroom, where he has set up a special, revamped area specifically for hand coating & printing. There is a special spot reserved for the printer. We will carefully lay the Mylar sheeting onto the mounting board, then pop in the tubes, plug that girl in and see just how much UV power is really there. Doing a bit of online research shows that the corporate built UV printers run $10,000 or up.... Not sure what they are printing or for whom but I'm not inclined to believe such high tech machinery is the answer to a century old practice.....
I am also trying to find out just how UV light is measured, and how much this printer will put out. Being math was not be best friend in college I can grasp relationships mathematically, but actually applying the mathematical model is not likely forthcoming from me. The closest I could come to any sort of measurable output of UV light was gleaned from a internet site dealing with measuring UV light, apparently one which draws engineer types. Here's what I came away with.
The measurements used were for UV sources from about 5W to 15W. I am using eight 20W tubes, so that will have to be scaled up from this figure. (2) 15W fluorescent tubes equals 2300; or uW/cm2 = 2300. That based on a total of 30W output; my printer has 160W output, which is a bit over five times the total wattage output. My problem is simply that what does that actually mean? Does that mean my printer is putting out <12, 190>, and if so, what exactly is that figure's measurement? I don't mind admitting I don't know something, as long as I am working to find out. Perhaps there is a photographer out there who also has a grasp of UV light, or the math that involves measuring it, that is willing to comment or offer up some useful feedback. Perhaps, yet not all that likely for both counts to unfold.
Here is a clip from one such informative site;
"Lamp intensity is defined as the overall power of the lamp and is most often designated in watts. Also called power density, intensity refers to total lamp output across the entire electromagnetic spectrum. Lamp intensity generally affects rate of cure of particular products, since it is one of the factors determining the amount of light that actually reaches the product.
It is important to distinguish between basic lamp intensity and intensity or amount of light at the working surface. The quantity of light at the working surface is defined in either intensity units or energy units. Light intensity at the product surface, described by the term irradiance, is a measure of momentary exposure and is most often quantified in milliwatts/cm2. Light energy at the surface is a measure of cumulative intensity exposure (intensity x time), quantified as millijoules/cm2, and is simply:
mW/cm2 x seconds = mj/cm2"
End Quote;
That's what we're working with in terminology. UV printers were not something commercially available when I was last printing hand coated processes. The sun was my friend. One of the advantages of the light in central Oregon in the Willamette Valley, something we referred to as Zone VII skies, when a soft gray dome of light covered the sky, sometimes for days, or weeks. That diffused light measured around 15-30 lumens on a GE hand held meter, without wavering for hours at a time. The printing was excellent. Soon, I'll know just how well this UV printer really is, and I'll be making that the center of my blogging until there are prints arriving, ready for exhibition. Stay tuned.
Just came across listings for UV meters for $30. I want one....
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