More information provided by NAU American Southwest Virtual Museum: 

Dinwiddie Polychrome is type of Roosevelt Red Ware limited in form to recurved bowls, often with smudged interiors.  This type is found in southeast Arizona and southwestern New Mexico, and may not occur west of Kinishba and the Nine Mile site, Arizona.

Archaeological Culture: Salado

Date Range: 1390-1450 C.E.

Construction: By coiling.

Firing: In an oxidizing atmosphere.

Core Color: Brick-red, tan, gray to black.

Temper: Moderately abundant fine water-worn sand.

Surface Finish: Exteriors slipped red and polished, painted (black over white; frequently unpolished and gritty in appearance); interiors smudged.

Surface Color: Exteriors red (brown in over-fired vessels) and white, painted; interiors black.

Forms: Recurved bowls only.

Decoration:

• Paint: Black paint over white design fields.


• Pigments: Black: carbon, red: hematite, white: kaolin.


• Design: Exterior design is like Gila or Tonto Polychrome jars; interior is smudged; common motifs are simple repeated triangles, squiggles, checkboards, terraces, pendant flags, hatching, interlocking scrolls, and dots.


• Comparisons: Similar to Phoenix, Gila, and Tonto polychromes, but smudged on the interior and limited to recurved bowls.

Other Names: Dinwiddie Polychrome: Gila Variety; Dinwiddie Polychrome: Tonto Variety.

Information provided by Lyons and Clark 2012

"[...] exterior: decoration like Gila or Tonto Polychrome Jars, interior: Smudged." (Lyons & Clark 2012:20)

Lyon's & Clark description of decoration on Gila Polychrome Jars: Jar exterior: "(1) single horizontal band of white Slip and black paint, Jar base (below black-on-white zone) Slipped red, or (2) multiple, horizontal stripes of white Slip and black paint separated by stripes of red Slip." (2012:21); 

Lyons & Clark description of decoration on Tonto Polychrome Jars: "Jar exterior: (1) single design field comprised by panels or meandering ribbons of black paint on white Slip surrounded by red Slip, (2) separate design fields for neck and body, each comprised by panels or ribbons of black paint on white Slip surrounded by red Slip, or (3) separate design fields for neck and body: one comprised by panels or ribbons of black paint on white Slip surrounded by red Slip, the other consisting of horizontal band of whtie Slip with black paint." (2012:20)