thank you all, g_x, katharine, kerik, for your fine answers.

Troubleshooting a new process turns out to be very discouraging at times, especially in an early phase, thank you very much for your answers. I'll filter the dichromate solution and give it a try. And in the future I'll find a more reliable source for distilled water.

the pigment comment is especially interesting

i'll copy paste the thread for future reference

cheers,
can