A flour duster is a tool for sprinkling flour. You can use it to dust surfaces for rolling pastry or kneading dough, dust bread dough before going into the oven, or dust baking pans.
A traditional design is a set of thick coiled stainless steel wires attached to a steel handle. It will be 23 cm (9 inches) long altogether.
Pressing the handle opens the coils in half. You scoop up flour in the opened coils, then release the handle to bring the two sets of coils back together again. A spring keeps them both closed together.
You then hold the duster over the surface you want to dust, and press the handles slowly to start releasing the flour in it.
It is useful when using a decorative paper stencil on the top of a cake or loaf of bread.
A similar item, a flour dredger, is designed to release a heavier coating of flour.
Flour should be treated as a raw substance needing cooking; and only sprinkled over items that will receive further cooking.