You can use a bitmap file or procedural map to control the Roughness parameter on the Basic Parameters rollout. White pixels in the map increase roughness. Black pixels reduce roughness to 0. Intermediate values adjust roughness accordingly.
Roughness map adds a textured pattern to the vase.
Reducing the Amount of the Diffuse Roughness map reduces the map's effect, and increases the effect of the Roughness value on the Basic Parameters rollout. When the Amount is 0 percent, the map isn't used at all.
To map the roughness value:
3ds Max opens the Material/Map Browser.
(If you choose Bitmap as the map type, 3ds Max opens a file dialog that lets you choose the image file.)
Alternatively, you can use the Slate Material Editor to wire a map node to the Diffuse Roughness component.