If you don't have time to soak the fiber (trivia, this is called "retting"), you might try beating it out instead. Just get yourself a flat surface, lay the stuff out, and work it over with a light mallet until it starts fraying.

For the more technologically gifted cave man, I found a wire brush to be very useful in fiber work. Lay the brush bristles on a bundle of fiber, bear down to keep the brush stationary, and just pull the whole bundle through it. Has to be done while fresh.

I don't have direct experience with either of the fibers you mention so I'm really not much use to you. I can offer the insight though that blades are a no-go when you're trying to separate natural fibers. It's tempting to scrape, I know, but I have NEVER seen this work. The fibers are soft and bendy, and the blade bites into them too easily. You need to break the fibers apart either by mashing, tearing, or decomposition. This is assuming you need to break the fibers apart at all: the braided cord shown above is made from whole cattail leaves. If you're dealing with something of grasslike thickness and pliability, I'd try working it in the raw.

Let us know what you find out. <img src="/ubbthreads/images/graemlins/smile.gif" alt="" />