confectioners sugar
See also: sugar
Also known as: powdered sugar, icing sugar
Granulated sugar ground into a fine powder and mixed with a small amount of cornstarch to keep it from clumping, giving it a much lighter, fluffier texture than regular sugar by volume. Used for glazes, frostings, and dusting, where it dissolves smoothly into liquid without the graininess granulated sugar would leave behind.
Buying guidance
Any standard brand works interchangeably -- there's no quality tier worth shopping for the way there is with something like vanilla or chocolate. It's sold both plain and "sifted" on the label; either works fine once sifted at home, since it tends to compact and clump in the box regardless.
Substitutions
- Granulated sugar processed briefly in a blender or food processor with a little added cornstarch -- a reasonable homemade stand-in in a pinch, though it won't be quite as fine.
- Regular granulated sugar -- not a true substitute for a glaze, since it won't dissolve smoothly and leaves a gritty texture; only reasonable where the sugar is being fully dissolved into a hot liquid first.
Tips & common mistakes
It's much lighter than granulated sugar by volume, so a recipe's "1 cup" of confectioners sugar weighs noticeably less than 1 cup of regular sugar -- measuring it packed down rather than spooned and leveled can throw off a glaze's consistency. It also clumps readily in the box or bag, so sifting before measuring (not just before using) gives a more accurate amount.
Storage
Keeps indefinitely at room temperature in a sealed container or resealed bag -- it doesn't spoil, but will absorb moisture and harden into clumps if left exposed to humid air.