What's the difference between the Sulky 30 weight and 12 weight Cotton Threads?

The heavier 12 wt. Cotton is a dramatic looking top thread in both the Solid Colors and the Cotton Blendables. We generally recommend using the 12 wt. on the top (although it is used for bobbin-work as well), and the matching, lighter 30 Wt. in the bobbin.

Also the 12 wt. solid colors and 30 of the 12 wt. Blendables are now available in the 50-yd. Petites spools, perfect for handwork or small projects.