Re: continued solarplate notes
Well, results of two tests, for whatever it is worth:
I proved to myself my theory holds water. I did a solarplate at 8 mn aquatint/8 mn positive in full on direct HOT sun. I normally expose solarplate 3.5/3.5 to 5/5 under 15 watt UVBL. I got a perfectly beautiful tonal range of 7 stops from white to black.
Considering that Mike Ware says the sun is several times more powerful than UVBL (anyone know the exact comparison?) this is enough proof to me that there is a quite wide range of acceptable exposure and that the ratio is where it's at.
I exposed a KM73 plate to 8 minutes (!) aquatint but cut the positive exposure to 3 mn to relate to my 2 mn/45 ratio I found under UVBL with this plate (haven't tried the 49/41 ratio outside yet) and sure enough I got a usable image, although a bit on the bland side. Same hot sun, direct sun, but the deepest black on it corresponds to 1 stop less black than the solarplate deepest black. This stands to reason since my solarplate exposure is usually 2.5 to 3.5 more than the KM73 plate exposure. To have a range of exposure from 49sec/41sec UVBL 15 watt to 8mn/3mn outside full sun is a pretty dramatic indication of latitude.
Interestingly, I don't see a (dramatic or otherwise) difference between the sun exposed plates and UVBL, yet, anyway. I got four Newton ring spots still even though I powdered both sides of the screen and positive and the top side of the plate.
----- Original Message ----- From: "Jon Lybrook" <firstname.lastname@example.org>
Sent: Sunday, April 08, 2007 5:25 PM
Subject: Re: continued solarplate notes
SusanV wrote:Hi Susan,Jon, the Dan Weldon screen isn't that dense at all. I'm getting the same exposure times as you are, adjusted for my 1000k lamp.