You should now understand at least some of the basic principals involved in processing of powders. This TLP does not cover all aspects of powder technology - for example, there is nothing on production of powders, on their classification into different size ranges or on their safe handling. Nevertheless, much of the underlying science, particularly that governing the dynamics of particles in fluid streams, has been covered here and you should be able to carry out simple calculations concerning sedimentation of powder particles in fluids and on whether they are likely to strike obstacles in a fluid stream - this is relevant, for example, to their removal by filtration and to the process of thermal spraying . The significance of the Reynolds number, the Stokes number, the Biot number, Darcy’s law and the permeability of a porous medium are all described in the context of powder processing. Moreover, the procedures that are commonly used to produce artefacts from metal and ceramic powders are described, although there is no quantification of the sintering phenomena that take place during them.