Loom Weaving Beads With Two Wefts

When using two wefts, 1) the first weft is used to bring the row of beads behind the warp and 2) the other is threaded in front of the warps to secure that row. That second weft is then used 3) to bring the next row behind the warps and 4) the first weft becomes that row's lock in front of the warps, and so forth.

Notice that the main difference is the way that the edges of the piece are finished. With a single weft, the right edge is always just a capture of the rightmost warp, while the two-weft method goes from row-to-row on BOTH edges.

Other differences are that your tension on the weft is easier to control with two wefts (more important on wider pieces) and that you have two more ends to sew into the work when finished with two wefts.