impression depth w. polymer plates

Someone posted awhile that polymer allows to get deep enough imression. My experience has been (my plate is from Boxcar), it works well for kiss impression, but for deeper bite I start getting little blotches on paper, which I think come from plate edges. I did cut blank plate away from design as much I can, but still the problem


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I wouldn’t cut the plate away from the design at all if you are looking for a deeper impression. The plate edges will show up on the sheet with or without ink.

There is a deep relief plate and base from Boxcar, but if you already have that then the only other alternative would be metal, either as plates, or type.

I had this problem pretty consistently and could not figure out how to solve it after trying different things.
Finally…. just last week (!!), with the help of a really nice letterpress expert, I realized two things:
1. I needed to adjust my packing—you should use a hard packing…
2. My rollers were not at the correct height. They were hitting the photopolymer plate too hard, causing my plates to be way over-inked. My prints were not crisp because everything was over-inked, even thought I was using very little ink… and the rollers were inking the areas that had no design, leading to issues with ink printing in blank areas on my paper. So frustrating, but once I adjusted the rollers, I realized they were no longer inking any area of the photopolymer except for the type/design. When I had read about rollers being “type high,” I didn’t really understand what it meant until very recently, and it has saved me… I just purchased a roller gauge to help with roller height issues. If you want more info on getting one, I can send it along. Now I can achieve crisp and deep impressions. Yay!
Best of luck to you… I hope this helps.

It is just too much packing where it isn’t needed. If the extra packing needed for heavy impression is localized to the image area, the non-image area won’t indent the stock.

The lowest relief boxcar plates have a relief of .03”. The caliper of extra, extra thick paper rarely exceeds .025”. If you are having issues with a deep impression I doubt it is the plate.

Also remember that you can always look closely at your plate to see how inking is proceeding. Don’t be afraid to remove the chase if you need a closer look. You want even, consistent inking across the face of the plate, and little to no ink along the edges.

I am not trying to get really “deep” impression, just want to get some bite so it’s deeper than the kiss. There’s not much packing there, the stock I use is fairly thick, it’s 300 watercolor paper. Works nice, but when I try to add packing to get deeper I start getting these belimishes.

anniebpearl- tell me more what do you mean “use a hard packing”. I hear you on the rollers, I did some of it. I used tape to raise them all the way up and one guy with roller gauge checked it and said I am right in the sweet spot!
Well the prints came out like the plate wasn’t getting enough ink, so I took off some of the paper. Prints started looking good, but only for kiss impress.

there’s been some talk that watercolor paper is not a good paper for this process as well:

As always… pictures, pictures, pictures.

Have you tried dampening the paper?

Never did that; my impression is it’s used to get large solids filled evenly otherwise letterpress won’t fill solid areas that well. Am I right? tell me more

Watercolor paper is not designed for printing. It is harder than printing or printmaking papers and not as receptive to printing ink. You need to dampen it to soften the fibers and maybe remove some of the sizing. It isn’t just a matter of printing solids. Type matter will print better and with less ink and pressure.


Actually, papers made for watercolor should not be dampened, they are made to resist this. As an example, Stonehenge. Sucks if it is dampened. But dry, and with a good whack, not bad at all. Learned this from a student. Where all the best ideas come from.


Well, Gerald, my only experience with printing watercolor papers is with Fabriano Artistico; dozens of reruns over the years of a 2c/2s business card on the cold press finish, and just last week an award on the hot press. And I’d say that particular sheet is hard enough that it really doesn’t take much of a bite even on a larger press, compared to cotton printmaking or book papers. If one is trying this on a small press or tabletop platen, and needed a visible bite, then softening the fibers through dampening would be the next thing to try. No?
Stonehenge is a multipurpose paper for printing, printmaking, drawing and other media including watercolor, but it isn’t primarily a watercolor paper, so it must not be sized as are other watercolor papers.

What will that entail -dampen it to soften the fibers?

Dampening cotton paper for printing has been discussed here a number of times, so a search of the archives here will show you some of the differing views and methods. You either spray, sponge, or dip (and printmakers soak). But the point is that moisture softens the fibers of the paper and makes it easier to print, requiring less pressure and ink. Only a little mositure is needed, and the ideal sheet is just cool to the touch but not wet to the touch; getting it right takes some experimentation. For register work you have to do all the printing before the sheet dries.

Are you using hot pressed or cold pressed watercolor paper?