I spent a long time trying to figure out in my head how warp pile cloth was constructed. I knew that there were two warps, one for the ground fabric, and the second for the pile. This can be seen by pulling on a single loop in a towel. Eventually I came to a kind of idea of how this kind of fabric was woven. It turns out I was correct. I couldn't think of any other way it could be done. "To produce the pile a wire is inserted across the width of the warp into a shed formed only by the pile ends. When the pile ends are subsequently dropped into the bottom shed and interlaced with the weft they remain draped over the wires as shown at ..... (snip) ... Thus, the cross-sectional dimensions of the wire determine the height of the pile. After the insertion of a number of picks (and wires) the wire furthest away from the cloth fell is withdrawn leaving the loops which were formed over its shank as a surface feature in the cloth..." - Watson, "Advanced Textile Desi