This is what happens to your hands when you strip the bark off alder with your bare hands. It’s no wonder that alder bark is used to dye fabric. The type of alder that grows in this area is Alnus rubra – red alder. It grows along the Pacific coast from northern California into southern Alaska. When you first strip the bark off, the wood is a pale yellow (see Posts – Nature’s Gift), but it soon darkens to a deep red-brown, and looks like it has been stained.
And here are some links about dyeing with red alder and other plants.