Choosing a High-Quality Cotton Thread
I learned to sew making garments. Often with garments, when choosing thread, you want a polyester thread. I learned the hard way that when you make a quilt with polyester thread the shrinkage is so different that the thread looks wonky after washing.
For 100% cotton fabric in quilting, I recommend you use 100% cotton thread. When choosing thread for quilting, you also need to consider the weight and the ply. When looking at thread numbers the top number is usually associated with the weight and the bottom number with the ply. The ply shows how many threads are wound together to make a single strand of thread. So, if the thread reads 50/2 like my favorite quilting thread does that means it is a weight of 50 and a ply of 2.
How Thread Weight is Calculated
The way in which thread companies determine thread weight is inconsistent so it can be very confusing. To help you on your quilting journey, and to keep it simple, I will include my favorite company and how they determine their thread weight.
Aurifil Thread: For Aurifil, a hank is 840 yards or 770 meters. Their weight is determined by the number of hanks necessary to weigh 1 pound. That means that for their 50wt/2ply, there are 50 hanks in a pound of thread. This means that the lower the number, the thicker the thread because it takes fewer hanks to make up that single pound.