To answer Katie's question:

Synthetic yarns (generally) won't melt upon exposure to water (unless you're working with some of the funkier Habu Textiles things made of paper and such). But you do want to be careful with the heat.

I think you can sort-of block acrylics and others, following the typical blocking instructions for wool - warm water, pin it out, let it dry. Or, alternatively, pin it out and hold a steam iron on high steam above it. But this is very important: do not touch the iron to the garment, it can melt, or if it doesn't, it gets shiny and nasty.

There's also the practice of "killing" acrylic.
Some people use the term interchangeably with steam-blocking, but I've also seen it used to refer to (a) machine washing and drying on hot with a long cycle or (b) "whapping" it during the process of steaming. I don't recommend (a), synthetics in a hot dryer can lead to very undesirable results (up to and including partial melting).

if the problem is the scarf edges rolling, and steaming doesn't fix it, another alternative would be to get narrow grosgrain ribbon and sew it on the "wrong side" of the scarf, right along the edge. It's not particularly elegant but if you choose a color that either blends or contrasts nicely, it will look like a "design element" rather than a "had to do it."

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taking Bess' quiz 'o' the week:

You Were an Eagle

You are able to rise above the details of life and see the big picture. A spiritual being, you tend to go beyond material concerns.

What Animal Were You In a Past Life?