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The basic fusing principle is to heat (fuse) the surface layers- between each application. Render the surface to high sheen and then quickly back off; the surface appears to just start to melt.
Further heat application can push (blow) the paint around; depending on desired effect.
Combination of heat application and other techniques will result in a multitude of surfaces. See Inlay or Intarsia, Intaglio, Carving Tools, Metal Sculpting Tools, and Printmaking Scrapers for more info.