I never knew this was called French Bias until The Book. I’ve always referred to it, and purchased it as, double fold bias tape. Anyway, The Book says, “The difference between the two bias treatments is that a single bias binding starts as a single layer of fabric and the French bias binding starts on the fold…the double folding is appropriate for sheer fabrics to conceal raw fabric edges and add thickness to the neckline or armhole edge.”
Prepare your bias strips at 2 inches wide.
Fold the strip in half, wrongs sides facing