Information provided by American Southwest Virtual Museum:

Gila Polychrome was one of the most widespread of the Roosevelt Red Wares.  Found almost everywhere south of the Mogollon Rim and in concentrations in the Roosevelt Basin, Tonto Basin, Gila Basin, Verde Valley, San Pedro Valley, and around Globe and Stafford, Arizona, this type as also been found occasionally near Winslow, Ajo, Gila Bend, and Nogales, Arizona; El Paso Texas and Casas Grandes, Mexico. (https://swvirtualmuseum.nau.edu/wp/index.php/artifacts/pottery/roosevelt-red-ware/gila-polychrome/)

Archeological Culture: Salado

Date Range: A.D. 1300-1450.

Construction: By coiling.

Firing: In an oxidizing atmosphere.

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

Carbon Streak: Common.

Temper: Moderately abundant fine water-worn sand.

Surface Finish:
        Bowl interiors: well-smoothed and coated all over with thick slip; usually crazed; slightly gritty; never polished.
        Bowl exteriors: coated with thin slip; usually well-polished, horizontal striations; occasionally also coated from rim downward about halfway to base with the same slip as used on interiors.
        Jar exteriors: well smoothed; coated with the same slip as used on bowl interiors from (but not including rim to point about midway between base and greatest body diameter; unpolished; usually gritty; crazed; inside necks and area below (white) slip, coated with thin (red) wash; well-polished.

Surface Color: bowl exteriors, red, sometimes white in part; bowl interiors, creamy white; jar exteriors, red and white; bases and other areas from which wash has weathered, color dull brownish to brick-red.

Forms: bowls, jars, figurines.

Vessel Thickness: 4 to 7.4 mm; average, 6 mm (jars).

Decoration: 
Paint: Black, dense, carefully applied.
Pigments: Carbon.
Design: bowl interiors usually completely covered in all over layout, frequently with fold design or horizontal band leaving open circle in bottom; decoration never carried to the rim; rim usually plain, occasionally ticked; bowl exteriors usually unpainted; on bowls having exterior white slip appears decorative band similar to band on interiors, with horizontal stripe just below rim, stripe almost always broken; jar decoration has horizontal stripe, usually broken, encircles shoulder, dividing white slipped area into two zones, one around the neck and one around the body; zones painted in bands containing elements similar to elements on bowl exteriors; rarely horizontal stripe just below rim, leaving only one decorative zone on white slipped area. Design elements consist of predominantly solid elements, running largely to tapering triangles and scrolls with scalloped edges; also solid steps, keys and small mazes; hachuring in triangular panels fairly frequent; horizontal stripe always present, usually just below rim, sometimes one or two inches below rim, dividing surface into two areas, decorated with horizontal band above stripe with all over lay-out below, stripe usually broken.

Variants: Gila Black-on-red: same as Gila Polychrome, but without the white design fields.

Comparisons: Pinto Polychrome, horizontal stripe or broken line absent; decoration carries to rim; use of balanced solid and hachured elements common. Tonto Polychrome, decoration employs red as an integral part of design on one or both surfaces; brush work somewhat less well executed.

Information from Lyons and Clark (2012):

"bowls, jars; interior: black paint on white slip (usually wide), black banding line at rim, over exterior: slipped red; 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."

Information provided from the Southwest Ceramic Typology Project:

Gila Polychrome was described by Gladwin and Gladwin (1930). This type refers to Salado Polychrome forms that developed out of Pinto Polychrome(Crown 1994; Hayden 1957; Lindauer 1994; Young 1982). Gila polychrome appears to have been first produced around A.D. 1300, and it is most abundant at sites dating to the late A.D. 1300s. It lasted into the middle 1400s (Crown 1994; Lindauer 1994). Gila Polychrome is represented by both bowl and jar forms.

Gila Polychrome bowls consistently displays distinct buff or cream colored slips on the decorated surface, although reduced examples may be white to gray. Exterior surfaces of bowls exhibit a red slip that may cover the exterior surface. On jars this red slip may occur as a band around the base and as a band near and around the neck. . Painted decorations are usually in a black organic paint on light colored pastes, sometimes in combinations with painted decorations in red clay. Painted designs of Gila Polychrome usually begin as bands or life lines directly below the rim. These may occur as wide isolated lines that may occur as a series of connected triangles or squares, or as thin lines incorporated into a group of solid motifs. The lines occur on the jar exterior at the bottom of the neck or below the design band, and may be continuous or exhibit a break. Gila Polychrome painted designs tend to be bold, large, and fairly simple. Motifs appear to have been expediently executed with relatively few brush strokes. Painted decorations cover much of the surface, and often result in the creation of negative designs in empty space. Solid designs predominate, although hatched designs may be present. Hatching, when present, tends to be thicker on Gila Polychrome when compared to earlier types. Motifs are often organized into complex rectilinear and curvilinear abstract representational figures. Painted decorations on bowls cover much of the interior surface. This decoration does not extend to the rim, but usually begins with an isolated or incorporated encircling line near the rim, filling the remainder of the interior. Designs on jars often include a banded design framed by lines along the neck and a larger design covering all of the remaining part of the vessel except the lowest part of the base. Areas between painted designs and the unpainted base are often covered by unpainted bands of red slip.