From: Judy Seigel (jseigel@panix.com)
Date: 10/02/03-07:39:45 PM Z
On Mon, 29 Sep 2003, Sandy King wrote:
> I have not found that an exposure meter gives an accurate indication
> of actual UV light as it relates to printing density in stops. The
> best way to test for uniformity of illumination is to expose five
> sheets of sensitized material of a UV sensitive process to a Stouffer
> step wedges. Make all five exposures at the same time, and for the
> same amount of time. Put four of the sheet at the extreme corners of
> the easel, and one in the exact middle. Develop and evaluate the
> densities and this will immediately tell you how uniform your light
> is.
>
I tested my Nu-Arc, what was the number, 26K ? -- with a bunch of 21 steps
along the edges and a few in the center. I found that the center was
pretty even (tho I didn't test every spot) but there was some fall-off in
about the outer inch or inch and a half. This was, BTW, with cyanotype,
not gum...
Is it possible if a plate burner is testing uneven that the glass over
the bulb needs cleaning? Or maybe the cover glass...??
J.
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