gampi palladium sensitizing problems

I'm printing on Gampi, both 90 gsm and 20. It's been successful, except for black spots, with a small smudge after them. That tells me it happens during sensitizing, but I can't find the source. I've checked all my materials, brushes, chemicals, etc. Has anyone found the same problem, if so could it be something in the paper itself?

Vern

Your description makes me think you have iron particles in your paper and/or brush. (More likely, the former...) Probably the paper was contaminated with iron particles in production and/or on their way to your and/or in your storage / workplace. (???) If you absolutely want to use this paper (or that particular batch), you may try to pre-treat the paper in 5% HCl for 3-5-10 minutes (= the minimum time that seems to be enough...) and rinse well later... Beware, that's not a good-practice, because while getting rid of iron impurities in the paper, you're also weakening it in the long term!

Ok, as it came to my mind, that could be something else: Check all your solutions for undissolved matter too. You don't want any crystals and stuff hit the paper while sensitizing.

Hope this helps & good luck!

Thanks, I think you called it right! I found some crystals in my platinum. Easy fix now.

Vern

Try to heat the solution in a water bath (30-40C - warm, not hot!) before filtering; it may go back in solution when warmed...