Heavy or Light?
(Thread has a weight issue.)
The lower the thread weight number, the heavier the thread. I know that seems backwards, but it's something to get used to. Let's take a look at some threads, their weights, and what they can be used for.
30 weight thread is heavier than 40 weight thread. Both 30 & 40 weight work great for embroidery.
Sulky Rayon 30 weight thread is about 1/3 stronger and thicker than their 40 weight thread. Most of the computerized embroidery designs today are set for 40 weight thread, so there is a large range of rayon machine embroidery thread in 40 weight.
30 weight shows up better for decorative topstitching. Anytime you want a heavier feeling and more visible look, go with 30 weight thread.
30 weight cotton is a favorite of quilters because of its strength and the sheen of its natural fiber.
Construction and lightweight threads are perfect for seams, lingerie, and heirloom items.
Standard construction thread is usually a bit finer for making your seams less bulky than you may find with some heavier threads. You can also buy fine construction sewing thread, perfect for lingerie or heirloom sewing with laces and really light, sheer fabrics.
Heavy, strong buttonhole twist thread creates lasting button shanks and buttonholes. You can also use it for topstitching.
Heavy denim topstitching thread--great for jeans and jackets--looks and feels like thread used in name brand jeans.