[Alt-photo] Re: UV lighting

[Kees Brandenburg]

Hi Laura,

Philips HPR125 bulbs need a balast (transformator) in the circuit. With one lamp you can expose pretty large prints by adjusting the height. But at some point exposure times gets too long. Compared to a bank of UV fluorescent tubes HPR125 need 2 stops more expores 8 min vs 2 min. in my setup.

I use both in my studio and kind of like the HPR, more a point light source and less diffuse, which gives somewhat more punch to a gumprint.

By the way, this is my bank of UV TL: http://polychrome.nl/techlog/simple-and-cheap-uv-unit

Kees


On 19 okt. 2013, at 15:53, Laura V <laura at lavatop.com> wrote:

> I had been using a vacuum light unit (used by plate or screen printers at my local printmakers' studio) for my UV exposures which worked great, but the bulb burned out (and no plans by them to replace).
> 
> My alternative is one of these: http://www.lamptech.co.uk/Spec%20Sheets/Philips%20HPR125.htm
> which someone from this list was kind enough to send me a few years back (thanks John if you are still here!). Has anyone used one of these? I'm assuming this will be good for smaller sized prints - the specs say the angle of the reflector is 30°. Would it be possible to move the bulb farther away for a larger size, or somehow use reflective material to increase the area size, or is this bulb just not powerful enough for that? Also, do I need to use a fan with this lamp? I am thinking of putting it inside the printing unit below the vacuum press.
> 
> If this lamp doesn't work when I decide to go larger, I'm limited to either what's available locally or what I can order on the internet. What's available here are grow lights, fluorescent or mercury halide. My confusion lies in the fact that these are listed in color temperature, whereas recommendations for gum printing are usually given in wavelengths. Is there a correlation between color temperature and wavelength? Is higher color temperature necessarily better (do they produce more UV in the suitable wavelength)?