I've used a clothing steamer brush (handheld electrical appliance, holds a litttle water, squirts steam out from around a flat brush attachment) a couple of times to reduce excessive waviness and curls out of both human and synthetic systems. Works fine, and so far I've seen no signs of permanent damage as long as you don't over-do it.

Here's mine at Amazon (though not currently available), so you can see what I'm talking about:

<!-- m --><a class="postlink" href="http://www.amazon.com/Rowenta-DA-55-Clothes-Steamer-attachment/dp/B000XS5H4S">http://www.amazon.com/Rowenta-DA-55-Clo ... B000XS5H4S</a><!-- m -->