Thread thickness is labeled with a "Weight" (wt) or "Tex" number. Confusingly, the numbering system for "wt" is backward: .
: A natural fiber best for 100% cotton fabrics and quilting, as it ages and shrinks at a similar rate to the fabric. Specialty Fibers : Silk : Strong and fine for delicate tailoring.
: Heavy-duty and exceptionally strong for upholstery or leather.