I think I have some tussah silk. If it is, it has been bleached because it is white. Last night, I dyed some with Veniards yellow dye, then I just pulled it out of the dye bath, dropped it in a can with a bit of vinager, sealed the top with foil and baked it at 275 for about an hour. It didn't get to 275 because the vinager hadn't evaporated when I took it out but after rinsing it thoroughly hardly any dye at all leaches out at all. The material I dyed last night would be just fine for dry fly dubbing and I think if I cooked it a bit longer and/or a bit hotter it would set completely. It looks like alot of heat is the secret to dying silk. All the dying sites I could find on the web recommend acid dyes for silk but nothing special was mentioned about setting the dye.