When I've looked at scarves in stores, I've noticed that when the warp is multicolored, the weft is a fine thread in a neutral color. Is that how a warp-faced scarf is woven?
Thanks for thinking about this.
I think the best answer to this is: not necessarily. It is most efficient for industry to arrange all complicated color orders in the warp (in order to never have to change weft colors during the weaving process). This is efficient for handweavers, too, but it would be especially so if you were weaving a great many items on a very long warp. The weft in a warp-faced or warp-emphasis fabric is not intended to show, enhancing the warp colors and providing warp-way drape. So, the weft is probably a neutral color—and fine—simply so it won’t affect the warp colors wherever it peeks through. As handweavers, we are probably more likely to experiment with weft colors, even if their effect is subtle.