Sulky Metallic Thread Rainbow - Blue. SULKY-165 yards of metallic thread. A strong polyester core wrapped with metallic foil. Cross wound spools with snap-end caps. Completely washable. Works in sewing machine and serger looper. Can be used in a bobbin. Excellent flexibility for decorative hand stitching. Use an 80/85, 14, or long-eye top stitching needle.