COATS & CLARK S964-8630 Extra Strong Upholstery Thread, 150-Yard, Driftwood Upholstery Nylon is a heavyweight 100% nylon thread for machine and hand sewing indoor and outdoor heavyweight fabrics It is a bonded 3-ply nylon thread that is weather abrasion mildew and UV resistant For best results use a size 18 needle and increase stitch length