This interesting bolete grows in Europe and I was lucky enough to be gifted it from Norway! I worked with it dried and used the entire mushroom, not just the caps. For all boletes I make an acidic bath using vinegar at pH4 and for some boletes I work with a 2:1 ratio but I decided to work 1:1 to see what kind of color it produced. It produced a beautiful array of gray olive green, golden orange and mustard yellow. Like most boletes they are challenging to lake because the pore surface, all the little tiny tubes, are hard to filter out. It makes a gray white colored pigment that mulls to a beautiful, glimmering brown paint.
I met Michael Spurgeon at the UC Berkeley Botanical Garden years back at a Michel Garcia workshop. We immediately connected on mushroom dyes and have been sharing tips and tricks on our experiments and results working with mushrooms for color. Michael has been incredibly generous with his knowledge and gifting mushrooms to me to include in the Mushroom Color Atlas, including Cortinarius californicus and passing along Neoboletus praestigator from Norway.