They're fantastic!
I make inks and paints from natural materials too, but I keep it completely foraged other than sometimes adding a pinch of baking soda or vinegar to change colors. I got a grant from the Minnesota State Arts Board to write a book about it and to do free community workshops for kids and adults. The resulting art projects can change colors over time, sometimes to really astounding degrees (magenta art pieces look black the next day and then green the next...) and sometimes they don't change at all. The paints and colors we have are different every time we do it according to what is growing wild or what is in my garden or even fridge.
We generally use a mortar and pestle to grind the materials with a tiny bit of water, with the exception of berries. Berries are fabulous because if you freeze them it will break the cell wall and when they thaw they release all this wonderful deep rich juice (think of thawed blueberries). And with most blue or purple berries, you can completely change the colors with an acid or base because they are pH reactive (the anthocyanins do it). We can also make wild mushroom ink in a couple of hours by literally just letting mushrooms like inky caps sit in a jar on the counter for a couple of hours and they melt into ink.
We use foraged clam shells for the palettes and they dry into little portable dry paints that you can use like traditional watercolor pans. We make easy paintbrushes from the top and bottom of a found feather inserted in a foraged hollow stem.
The book I wrote with the projects (and a lot more, like how to find and forage wild clay, make paper from invasive plants, make color changing paper, make invisible ink paintings, etc.) is Wild Art: Awesome Art Projects Using Wild & Invasive Plants & Other Nature Items (aff link:
https://amzn.to/4gDylT0).
My goal with it was to have all the projects be things that children could do without having to buy additional materials or to do things they'd need an adult to help with (like boiling down natural watercolors on the stove or using toxic chemicals). I wanted them to be able to make truly cool art projects for free or virtually free, entirely from natural materials. It's a kids' book, but I do workshops all the time for adults who also really have fun with it. I even did an Inktober challenge where I did a little 5 minute art piece every day of October with a different wild ink/paint I made that day. :)
Here are a few pics of some workshops we've done. I love that we do it in all seasons and there's always something different with different colors. I even keep my dried flower petals and such in a basket for people to play with. Dried red poinsettia leaves make the coolest paint/ink -- it starts out blood red and then dries to nearly black, and then a couple of days later it's a gentle gold that persists (the cat in the upper left corner of the Inktober collage was painted in poinsettia leaf ink), but it will also dry to different colors depending on if you grind it with vinegar or water. I'll include a few pages from the book too, and a collage of some of my Inktober little daily doodles. I've had so much fun with this project!
