I now know one way to create a faux verdigris finish on paper

Day 5: verdigris
Pencil sketch—>craft paint, masking fluid—>pen—>watercolors.
P R O C E S S N O T E S
I went in search of something as a reference image for verdigris. Google gave me the Statue of Liberty, some skeleton keys, and lots of door hardware. I then flipped through my old photos and found The Thing To Draw.
An old garden marker poked in the dirt of a spent flower box covered in what some consider to be weeds: morning glories.
The marker had a fine patina of verdigris and to replicate this on paper, I experimented with metallic copper craft paint, masking fluid for the letters, with a film of paint dabbed on then wiped off.

Dark turquoise was the winner out of five possible shades for the overcoat. I dabbed some white watercolor over the dried paint and that seemed to give it a more realistic verdigris finish.

Finished it with watercolors and a photo of the card nestled in some weeds.
Done. Until next time, may your paint flow freely, your brush bristles have no strays, and your blank canvas beckon you to create.