Most of the items I wet block are made out of wool, silk or cotton. This shawl was made out of a Rayon/Metallic blend and as you can see it blocked beautifully. If you're not sure how your yarn will block, try knitting a swatch and testing your blocking method on that first. (Or, you can always go look at other projects created with the same yarn on Ravelry, but it is still best to check yourself, first!)