Unfortunately the mushroom was quite old and maggoty, so I could not dye with the pores.
This bolete stained blue, but acid quickly restored the original colors. Nothing I tried was capable of fixing the blue color. I have no idea what compound causes the staining.
I have no idea how this color will age. It's acid-fast, at least. :)
There was one serious hazard involved in this project: the dye bath smelled delicious, like garlic roasting in butter! The odor permeated the whole house. My housemates were quite disappointed to learn that it came from a poisonous mushroom (nearly all red-pored, blue-staining boletes found in the US are poisonous).