gampi palladium sensitizing problems

[Miller]

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

 

[Loris Medici]

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!

 

[Miller]

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

Vern

 

[Loris Medici]

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