Sifting pure icing sugar
Q: Why does pure icing sugar go hard with lumps and is there an easy way to sift it?
A: Pure icing sugar, because it is essentially pure white sugar that has been ground to a powder, will go lumpy if it gets even the smallest amount of moisture in it. You will find that if you store pure icing sugar for extended periods or if you don’t store it in a well-sealed container, you can expect it to become hard and develop large lumps, which can be really tricky to sift. However, processing it in a food processor to remove those pesky large lumps first will make it so much easier when it comes to sifting.
Also, remember to only sift pure icing sugar just before using it as if it is left to sit on the bench for any length of time (particularly if the day is humid) it is likely to absorb the moisture from the air and quickly become lumpy again!