When a Navajo weaver says two warps, she means two pair or four actual threads per inch. A Navajo weaver always counts her pattern by inserting the batten and counting the warps that cross it. The warp threads are the vertical threads, the yarn initially stretched on the loom in preparation for the actual weaving. Warp yarn is a thin, tightly spun yarn with inherent strength as it must be able to withstand great tension.
Weft threads are the horizontal threads that cover the warp threads, or the yarn that is woven over and under the warp and from side to side. Weft threads are consequently a larger, fluffier yarn, intended to completely cover the warp. It is this yarn that is responsible for the beautiful texture of Navajo rugs. Wefts per inch are counted on both faces of a fabric. When the wefts are counted on one side, this number is doubled, as there is a corresponding weft on the other side. Weft count is approximate, since sometimes it can vary from the bottom portion of the rug to the top. It becomes increasingly difficult for the weaver to beat down the warp near the top of the rug, compared to beating it down near the bottom and middle. The more accomplished the weaver, the more consistent the weft count will be throughout the rug.