This afternoon I got in a little leaf collecting and pressing, which led me to thinking about printing...
Winsor Green YS watercolor and Holbein Rich Gold gouache. In this first image, the fern sections were brushed with color, placed on sketch paper, and pressed with heavy cardboard. After trying various consistencies, it just seemed that the watercolor didn't detail, although the gouache was showing promise.
Switching to Oxide of Chromium seemed to improve detail. Was it consistency, opacity, or both? Not sure about that, but I did like the color combination. For these last two test, instead of painting the fern sections, paint was applied to cardboard and the fern positioned and pressed into the paint. I somehow accidentally switched over to Holbein Brilliant Gold Gouache (duh...) and those oversized sparkles reduced detail.
I liked the look of the overlaid gouache so dropped bits of gold gouache on the Oxide of Chromium before pressing the fern into the paint. There is kind of a nice sparkle on the printing that's missed here.