When Should Top and Bottom Threads NOT match?

In most cases, it is recommended to use the same type and weight of thread in the needle as in the bobbin. This creates a balanced stitch that is equally strong on both sides.

There's an exception to this rule, though - when doing appliqué, embroidery, or other decorative work, we typically use a heavier thread in the needle and a light weight thread like Mettler Silk Finish 60 weight cotton thread in the bobbin.

Using the heavier thread on top allows for a more visible decorative stitch, which falls slightly to the backside of the project. This way the decorative stitching lies nicely on the front of the project. The lighter thread in the bobbin allows the project not to be too bulky and keeps the bobbin thread from showing on the back of the project.

For this appliqué project, we used 50 weight Silk Finish multi in the needle and 60 weight Silk Finish in the bobbin.

For this monogrammed tie, we used PolySheen 40 weight embroidery thread in the needle and Metrosene 50 weight all purpose thread in the bobbin.

For very fine embroidery projects, you may use 60 weight thread in both the needle and the bobbin, such as with these monogrammed handkerchiefs.