uv filter in color printing

[dale_cress2]

<p>I`ve just got started making color prints. I have an old Beseler condenser enlarger, a set of Kodak viewing filters and Kodak cp filters.<br>

The cp filters have a UV16 filter. My question is when to use it and when not to.<br>

Thanks, Dale</p>

[Alan Marcus]

<p>When printing color negatives it is recommended to keep a UV filter in the filter pack at all times. Initially when I questioned Kodak engineers, many, many years ago, I pointed out that UV was unlikely to transverse glass thus the lens should be sufficient to protect the paper from these short wavelengths which all emulsions are sensitive too. The answer was, we do want to avoid UV exposure at the paper plane. While the UV does this task, if mounted above the filters, it protects the filters from UV exposure which over time fades the dyes used in the CC and CP fitters.</p>

[jim_momary]

<p>Question ... if it is a standard condensor enlarger with the typical tungsten light bulb of 100 Watts +/-, then shouldn't the amount of UV produced truly be negligible?</p>

<p>According to spectral charts I've seen, standard tungsten lamps output less than 1% of the wattage as UV (i.e., < 400nm). Here's an example -</p>

<p><a href="http://heelspurs.com/a/led/black3.gif">http://heelspurs.com/a/led/black3.gif</a></p>

<p>Of course UV filtration wouldn't hurt anything, but I wonder if it's of any utility whatsoever?</p>

<p>Jim</p>

[Alan Marcus]

<p>Every color printing set-up, per Kodak, should have a 2B UV filter atop the filter pack. I have on occasion omitted the 2B without seeing any ill effect. High speed photofinishing machines have super powerful lamphouse. Exposure times 1/3 of a second or less. In these machines I always installed 2B. Maybe the recommendation stems from Color Print and Process who designed these high speed printers? </p>