Texture issue in homemade powdered sugar The other day I was making marshmallows and ran into a multitude of problems -- broken candy thermometers, overheated mixers, syrup spill, you name it. I thought I'd escaped the clutches of fate and made decent marshmallows until I realized I ran out of powdered sugar. 

Well, darn it. I had a big batch of marshmallows already made and ready for coating.

So I remember hearing you can make your own powdered sugar with granulated sugar and cornstarch. I gave it a try in my food processor and it kind of worked, but was still too coarse. 

Is there any way to get around this besides to keep on pulsing and hoping for the best? Does a blender, coffee grinder, or another kitchen contraption work better?
I'm gonna guess you just didn't go long enough.  I make my own in the food processor all the time, but I turn it on high, go have a snack and come back in 10 minutes.  It certainly does take quite some time.