“No. 50,” “50 weight,” and “50/2” may all mean the same thing—or they may not. For The Quilter’s Appliqué Workshop, I group threads into general categories of size and refer to them by a number that’s simply a rough consensus among the various manufacturers’ labels. This is a system of convenience rather than technical accuracy; the technical details are well explained in YLI’s “Thread of Truth” booklet.
The examples given in the table are threads I’m familiar with, but it’s by no means exhaustive—your thread stash will likely include others.
|Size 100||Very lightweight thread, good for hand appliqué.||
YLI Silk No. 100
|Size 60||Finer (lighter-weight) than regular sewing thread, often called fine machine-embroidery cotton or bobbin thread.||
Mettler Fine Embroidery No. 60
DMC Machine Embroidery Thread
Aurifil 50-weight cotton
Madeira Cotona No. 60
|Size 50||General-purpose sewing thread. Some variations in thickness exist between brands.||
Gütermann cotton sewing thread
Mettler Silk-Finish No. 50
Decorative threads, somewhat heavier than regular sewing thread. Cotton in this category is often labeled as machine-quilting thread.
Note: 40wt rayon and polyester machine embroidery threads are generally somewhat finer than sewing thread.
Mettler Quilting No. 40
|Size 30||Even heavier decorative threads. Cotton in this category is often labeled as machine-embroidery thread.||
Mettler Embroidery No. 30
Sulky 30wt Cotton and Blendables
Madeira Cotona No. 30
|Size 12||Very heavy thread, probably about the limit of what your machine can handle in the needle. Also suitable for hand embroidery.||
Sulky 12wt Cotton and Blendables
Madeira Lana wool
No. 12 pearl cotton
|Size 8||No. 8 pearl cotton|
|Size 5||No. 5 pearl cotton|
|Size 3||No. 3 pearl cotton|