Concept:
Mezzotint is an intaglio printmaking technique.
It is known for rich tonal effects and soft gradations from dark to light.
Burnishing is an important process in mezzotint.
Step 1: Understand burnishing.
Burnishing means smoothing or polishing a roughened plate surface.
In printmaking, burnishing helps create lighter areas by reducing the roughness of the plate.
Step 2: Connect burnishing with mezzotint.
In mezzotint, the plate is first roughened.
Then the artist uses scraper and burnisher to create tonal values.
The smoother the area becomes, the lighter it prints.
Step 3: Check other options.
Viscosity is related to ink thickness.
Intaglio is the broad family of printmaking techniques.
Planography is flat-surface printing.
But the specific burnishing plate technique is Mezzotint.
Step 4: Final conclusion.
Hence:
\[
\boxed{\text{Mezzotint}}
\]