Superfine sugar

Superfine sugar is granulated sugar with a much smaller crystal size. A baking textbook notes that granulated sugar is produced in various crystal sizes, with fine, super fine and berry among them, and that any size is possible at the factory depending on when the process is halted.

Because the crystals are small, superfine sugar dissolves quickly. This makes it useful in meringues and light batters, where larger crystals could leave a grainy texture or fail to dissolve. It also creams well with butter.

Bakers often use it for cakes, sponges and meringues, and it is the same product as caster sugar in British recipes. If you only have regular granulated sugar, a quick grind in a processor makes a fair substitute.