I do the same thing as Sarah, Jo, Pauline and neli. Just used it on my mermaid topper ( the right hand wrist and fingers holding on to the shell she is sitting on : http://cakesdecor.com/cakes/96428 )
I had to do it two times though may be my slurry had too much water :-)
Sasi, Sydney Australia, http://cakesbyssn.blogspot.com.au/, https://www.facebook.com/CakesbySasi