From: Sandy King (sanking@clemson.edu)
Date: 07/11/02-10:27:49 AM Z
Ed,
Is the Olec metal halide lamp you refer to below the same or
different from the one you used when we made some comparison tests
last fall in cyanotype and gum between your unit and my 5000K Venture
metal halide bulb. My recollection is that there was not very much
difference in speed between the two units when you had the Olec set
at 1000 watts?
Sandy King
>Sandy:
> There are two kinds of metal halide bulbs out there. Low voltage (= low
>temperature) metal halides are really just mercury lamps. Most low cost
>graphic arts lamps (such as the Nuarc) fall into this catagory. If you
>raise the temperature on the bulb ( as in the higher end olec and violux
>graphic arts lights), you can add other materials - such as iron - and
>thereby spread out the spectrum.
> I recently looked at the difference between an Olec mercury and Olec
>mixed halide lamp, and found that, at least for gum, the mixed halide lamp
>gives much faster exposures (2-3x as fast), and somewhat more contrast in
>the final product. Cheers, Ed Stander
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