From: Jeff Buck (jeffbuck@swcp.com)
Date: 11/12/02-10:17:06 PM Z
Clay & Sandy: Thanks for the suggestions. As you know, I have a metal
halide HID. I don't worry much about timing the exposure, because they run
6-8 minutes typically and I don't see how the 2-3 second fudge in my crude
timing system can make any difference. The intensity of the lamp is
another matter. When I got the thing last spring, I followed leads to get
an integrator, but pretty much crapped out when the glass-virtuoso guy
proved no help. On the other hand, looks like I should be doing a longer
warm-up. I've been doing 4 minutes because the electrician said 2-3
minutes would be plenty. As for the quiet time around the house, I can
manage that sometimes and I try to.... Say, are you guys saying that the
variations in temp and humidity I noted are probably not at issue? -JB
At 11:04 PM 11/12/2002 -0500, you wrote:
>Clay wrote:
>
>
>>Jeff:
>>
>>What are you using for your light source? And how are you timing it or
>>measuring it. I find I get pretty consistent results with the same
>>materials and ambient conditions... But I'm using a Nuarc most of the time.
>
>
>When using any UV light source without an integrator one is almost certain
>to observe some small differences in print density, even when all other
>things are held to absolute consistency. I find this to be true with both
>my bank of BL tubes and with the HID lamp when used without the integrator.
>
>If one must work without the integrator it is best to do so when the house
>is relatively quite and there are no large and sudden current drains.
>Also, for maximum consistency all light sources should be allowed to warm
>up for a few minutes before exposing. Two to three minutes is enough for
>fluorescent tubes, while HID mercury vapor and metal halide lamps need
>from 5-8 minutes to reach maximum output.
>
>Sandy King
>
>
>
>>
>>Clay
>>On Tuesday, November 12, 2002, at 08:58 PM, Jeff Buck wrote:
>>
>>>Actually, it's the tendency of a phenomenon to recur in the same
>>>form.... Anyway, after doing platinum/palladium for about fifteen
>>>months now, I find if very difficult to achieve. I arrive at a print
>>>that is satisfying. I want to repeat it. So, I use the same paper, the
>>>same chemicals (plain FO, pure palladium, PO w/ sodium dicromate
>>>mostly), the same exposure, and the same developer. As for ambient
>>>temperature and humidity, I can get pretty close to repeating,
>>>especially this time of year when I'm producing both artificially (by
>>>and large). Like the last couple days, I'm printing this negative, and
>>>the temp is between 65F and 70F, the humidity is in the range of 60% to
>>>70%. In each instance, the paper has been laying out in the area of
>>>that temp and humidity for a few hours; it's a little "heavy" and tacky
>>>to the touch. I guess I made four prints in these conditions (I was
>>>double-coating Platine, if that makes any difference). There were
>>>notable differences in the overall darkness of the prints and in degree
>>>of contrast. Would you expect discernible differences working within
>>>these variations in temp and humidity? How do you measure the
>>>temperature of the FO and platinum or palladium? I'm squeamish, maybe
>>>for no reason, about putting a thermometer into a bottle of precious metal....
>
>
>--
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