> Cor
>
>
> The answer is very simple.
>
> Your exposure is far too short.
.I realized that, so that's why my exposure became 15 to 30 min, on a
direct UV transilluminator! I exposue as also privately suggested by Bob
Schramm, until
"Don't worry about the length of the exposure. Use whatever it takes.
One way to judge is to expose until parts of the image begin to turn
purple. You might also get a slight image reversal. Cyanotype is
self-masking so its almost impossible to overexpose."
.and as you suggest...
I think that the strong blue base of my Xray film blocks a lot of UV, I'll
test that, and will mail my conclusions (if there is interest in that....)
>
> Expose until the shadows and lower middle tones are reversed and the highlights
> and the upper middle tones are dark blue. Then develop.
>
> Terry King
>
Cor Breukel
http://ruly70.medfac.leidenuniv.nl/~cor/cor.html
"The Infrared Gallery"
http://ruly70.medfac.leidenuniv.nl/~cor/cor.html