John
thank you for the link.
it is very informative and gave me a new wiew of the process.
i did a serie of 4x5" tests today in near clear sky with diff objectives from 65mm to 150 mm over 90 mm as well.
i found clear trace on both VC and brom paper, but no way near the beautifull pichtures in McCaws article..
hmmm- McCaw uses VERY large lensen.
in my stock i found a Leitz Epis 400mm f4.0. it is huge but no way near the U2 spy plane lens of McCaw.
mounted it on my wooden 8x10 camera. Under focussing i happened to put a finger on the sun on the mattgalss.
i burned the finger and started to worry about starting a fire.
during exposure the filmholder started to smell burned, but nothing furter happened.
after removing the brompaper a clear trace of of the sun burned all the way thru the paper.
i used the recipie from your link, i need to adjust the mixture, but it is definately better than my first trial.
if i get lucky, i will try to upload my result .
klaus