“+” before the mesh size indicates the particles are retained on and are larger than the sieve. “-” before the mesh size indicates the particles pass through and are smaller than the sieve. For example, if the particle size of a material is described as -10 +400 mesh, then 90% or more of the material will pass through a 10-mesh sieve and be retained by a 400-mesh sieve. If a material is described as -10 mesh, then 90% or more of the material will pass through a 10-mesh sieve.