Scanfil 50wt 2-ply Organic Cotton thread is proven for construction seams, quilt piecing, bobbin fill, quilt bindings, heirloom stitching, applique, paper piecing, overlocking. Will not shrink or bleed with washing. Recommended machine needle size: US 12-14/ NM 80-90.SCANFIL Organic Cotton threads are certified in meeting the stringent requirements of the Global Organic Textile Standard (GOTS). Scanfil Organic Cotton threads are also Oeko-Tex Certified for Standard 100. These threads are produced using the most premium cotton available, Pima Organic Cotton fiber that is grown without the use of chemical pesticides. The extra long staple Supima Organic Cotton is mercerized and spun using proprietary spinning process for ultra smooth “hand” and virtually no lint. All shades are achieved using only GOTS approved dyes and coatings with non-toxic solutions, including vegan solutions. Scanfil spools and cone cores are both biodegradable.