From: Sandy King (sanking@clemson.edu)
Date: 11/12/02-10:04:48 PM Z
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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