I have a cake that is completely covered in black fondant, and I need to get the powdered sugar off of it. I still need to pipe the design onto the cake, so I need it dry relatively quickly. Any suggestions on what to use? Shortening? Water? I really don't want it to be tacky. TIA!!

Use a paper towerl to rub a small amount of shortening all over. It will appear greasy/shiny at first, but will be fully absorbed after a while. You should be able to pipe right away.

Thank you so much!!