You can roll it out on shortening & avoid the powder issue all together.
Rae
Or use corn starch... this seems to come off fondant easier...
If you still have some residual, you can use an airbush and spray the cake with alcohol to get rid of anything left over...
[quote="WhenTalentsCollide"]Or use corn starch... this seems to come off fondant easier...
quote]
Really? - I always find cornstarch to be worse 
Steaming the cake lightly will dissolve any excess powdered sugar. Or you can buff over the cake with a ball of leftover fondant. You could paint with vodka, which will dissolve the sugar, but be warned - doing that can leave brush strokes, make the cake shiny, and leave it sticky...vodka takes ages to dry (something like Rose spirits, which is 95% alcohol works a lot better, it dries in no time at all).
Easier though to try and avoid the situation by using powdered sugar (or cornstarch if that's what you use) very lightly when rolling out - then it shouldn't be a problem.
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