and now we come back to thread... labels are crappy. in order to really get what you want and know what you have you nearly have to go to a manufacturer or a commercial ( industrial) supplier and ask the questions directly. I had a particular project that I was trying to do "period" correct and the finish and dye required linen or cotton thread.... try to find out ... at a typical "sewing" center you have all purpose , improved, super zoomy extra improved....but nothing about actual construction, tensile strength ,material..... from an engineering perspective common sewing stores are nearly useless.