The better grades of fiber yarns are extremely tough and long wearing, giving the finished rug a tough, long-wearing surface. Also they are finer than the grass fibers, giving a thinner, less heavy feel, but increasing the cost because of the additional labor involved and the increased number of picks. Three basic weaves are used to give variety:
The basket weave.—In this 2-, 3-, and 4-weft or filler, yarns are shuttled across the loom between each raising and lowering of the warp. This produces a weave resembling the broad, flat weave of a market basket.
The twill weave.—More complicated because it requires additional loom equipment or "harnesses." While the basket weave requires only two such "harnesses" (one to go up while the other goes down) in twill, the addition of more "harnesses," and chains to operate them, produces interesting variations. In the twill weave, three harnesses are used. Each warp strand passes over two filler strands and under the next two, producing a diagonal, ribbed effect, giving a heavier feel to the rug, and resulting in maximum yardage.
Jacquard weave.—This type requires a different loom, equipped with the jacquard mechanism described in connection with the Wilton process, but constructed to carry the much heavier fiber yarns. In this process each warp yarn has its own "harness" which is raised and lowered by the operation of the cards, punched like the rolls of a player piano, to produce the desired pattern. (See fig. 35.)
Color is introduced into fiber rugs both in the kraft as it is made, and by stenciling.
The ingenious use of contrasting fibers, such as sisal, cellophane, and fibers varying in color from dark to light and back again, are often employed to develop interesting weaves and patterns.
Wool fiber types.—Still another variation is achieved by combining wool yarns with fiber. This type is woven with fiber warp tightly bound together with a cotton warp that appears on the surface. Filler yarns are of alternating fiber and wool carpet yarns, so woven that the fabric is reversible. Pattern is achieved by the coloring of the yarns and by stenciling. The amount of wool varies to secure the result desired. It gives to the fabric a softer feel underfoot.
Wide ranges of colors, weaves, and patterns are now available in fiber rugs to meet all decorative needs. For custom, room-size rugs larger than 9 × 12, many of the most popular patterns are offered in broadlooms, in widths up to 12 feet.
Grass rugs.—Only in three localities in the world is produced the grass from which these useful rugs are constructed. It is the wire-like grass which grows wild in the marshes which dot the great prairies in Minnesota, Wisconsin, and the vicinity of Winnipeg, Canada. It grows to a height of 2 feet without a joint, and in the spring is covered with water which gives it the waterproof characteristic. When dry it is cut and, after curing, bound into continuous strands.