How do I make a frappuccino less watery? I'm trying to recreate a Starbucks caramel coffee frappuccino, but it's coming out awfully watery. I've watched them make it and here is what they do, as far as I can tell:


half fill the blender container with ice
pour milk on up to half the level of the ice
add some (hard to see how much exactly) coffee from a tank labelled "frap", which I assume is just regular cooled coffee
add some squirts of caramel syrup
blend.


Yum, delicious. But when I do this, I get a very watery result which is not thick and creamy like theirs. How can I improve it?
Aha, the article and comments on this site:
 http://www.squawkfox.com/2011/06/16/frappuccino-recipe/
suggest using double-strength coffee and (the secret ingredient) adding a pinch of xanthan gum. I might have to see if I can get that anywhere!