Advantages and Disadvantages of Threads
Cotton thread: Traditional quilts are made from 100% cotton. For quilts that you want to last for many years, 100% cotton thread will be your best choice, particularly with a pieced quilt top. A typical thread for sewing machines is 50/3. Some people like to use 60/2 in their bobbin, allowing a fine, smooth seam.
Polyester thread: Polyester thread is stronger than cotton, and comes in a variety of weights, colors, and finishes (matte or high sheen). It is more colorfast than cotton, and is strong and durable. 40 weight is typical for quilting, 60 weight for appliqué. The continuous filament is not linty like cotton. Polyester thread can cut through cotton fabric and is not as soft as cotton thread, so it is not a good choice for heirloom quilting.
Polyester Core Cotton thread: is a polyester core encased in cotton. This provides a strong thread with the traditional look and feel of cotton.
Nylon thread: Another continuous filament thread, nylon is referred to as invisible thread because it is so thin. When choosing nylon thread, you will want a very fine thread, like .004 or .005, either clear or dark, depending on your project. Invisible thread is good for appliqué or other applications where you don’t want the thread to show. You must be careful when ironing because this thread can melt or become yellow and brittle.
Decorative threads: Rayon, metallic, wool, and silk are all specialty threads used mainly for decorative purposes.