A test sieve is a scientific screening instrument, that utilizes wire sieve cloth mounted on a rigid frame to help generate a reliable particle size distribution curve.A sieve—also known as a sifter—is typically a basket made of a metal fine-mesh weave with a handle attached. Its job is to aerate and separate dry ingredients like flour, cocoa powder, and powdered sugar, which will lead to a lighter and more tender crumb in baked goods.