Granulated. I'm sure you could use powdered sugar but I've always used granulated. Try it and let me know how the powdered stuff works! 

To find "THE RECIPE LINKS ARE HERE" thread, click on "Forums", then "Recipes" and it's the first sticky. Latest updates are on (the bottom of) page 10 here: http://cakecentral.com/cake-decorating-ftopic-625803-135.html
To find "THE RECIPE LINKS ARE HERE" thread, click on "Forums", then "Recipes" and it's the first sticky. Latest updates are on (the bottom of) page 10 here: http://cakecentral.com/cake-decorating-ftopic-625803-135.html










