They're GORGEOUS! I'm having dyer's envy right now, haha! I've used alum as a mordant as well, though I haven't had it modify the colors like you experienced. Often my natural dyed fabrics fade disappointingly over time, but I think that is due more to my post-dye care (especially use of harsh laundry soaps) than any fault of the alum itself. Curious if you have experience with laundering naturally dyed fabrics?