C17    Discuss why different types of amalgams require different condensation pressures.

Different amalgam alloys particle pack differently. For example, spheres pack more efficiently than irregular particles. By improving the packing. the density increases and the quality of the amalgam improves.

In order to improve the packing density of the lathe-cut particles, they have to be displaced in relationship to each others. In order to achieve such a displacement, one most overcome an "internal friction" that exist between the different particles. That friction is lower for spheres than for lathe-cut particles. In addition, spheres pack more efficiently by chance. These considerations explain why spherical amalgams do not need as high condensation pressures as the lathe-cut amalgams. In fact. a spherical amalgam cannot be condensed with a small condenser under high pressure, because such a condenser will just penetrate the extremely plastic spherical amalgam.