Ikat - Twill Weave vs. Plain Weave - Mystery Solved
Indian ikat is plain weave. But Cambodian ikat (both that made by the Khmer majority, and that made by the Cham minority) is twill weave.* Parul Kushwaha of the Ministry of Textiles Weavers’ Service Centre, Bhubaneshwar, Odisha told me that some villages in Odisha used to make ikat in twill weave. Many of the patterns in Khmer ikat appear to have come from Odisha, and some (like the Chital) could only have come from Odisha. It appears that the practice of weaving ikat in twill came to Cambodia from Odisha.
But this just raises another question. Ashavali brocade today is twill weave (below left - look for the diagonal slant in the weave, most visible at the bottom). But Chorabab, which evolved from Ashavali brocade, is plain weave (below right - no diagonal slant).
Why is chorabab not twill weave? The most likely explanation is that, when Ashavali first reached Angkor early in the 12th century, it was plain weave. I will continue my research, but may find that this knowledge has been lost.
* I have seen Cambodian ikat made in plain weave for scarves, because they often flip over in the breeze - the same color is preferred for both sides.