In the Kitchen : Turn Clumped White Sugar Back to Grains

You want to bake some cookies, but when you go to measure out your sugar you find that is all clumped together and won't fit properly in your measuring cup.

Put a piece of bread into your bag or jar of sugar and in about six hours the sugar will be as soft and grainy as it was when you bought it.

The reason sugar hardens is because it gets dry. Once it begins to dry the grains of sugar stick together creating the large clumps that you found when you went to use it. Adding something with moisture in it, like a piece of bread, to the sugar increases the moisture levels and allows the sugar to re-granulate. If you don't have bread handy, a piece of peeled fruit or damp paper towel will also do the trick.