onderdraad

Onder draad is the thread used in sewing that forms stitches from the underside of the fabric. In most sewing machines, it is wound on a bobbin and sits in the bobbin case beneath the needle plate. The needle thread, called boven draad, passes through the fabric from above, while the onder draad is drawn up from below to interlock with it, creating a lock stitch. Balanced tension between de boven draad and onder draad is essential for a neat stitch; when tension is incorrect, the stitch may appear loose on the top or show loops on the underside.

The onder draad is typically made of cotton, polyester, or a blend and is chosen to complement the fabric and the top thread. Domestic machines commonly use a finer bobbin thread than the needle thread, but many combinations are possible. Bobbins are available in plastic or metal and come in standardized sizes compatible with specific machines.

In practice, correct threading involves placing the bobbin in its case, guiding the thread through the case’s tension mechanism, and threading the machine as for the boven draad. After winding, ensure the bobbin turns smoothly and that the thread unwinds correctly to prevent tangles and bird nests.

Common issues include uneven stitches, loops on the underside, or thread breakage caused by incorrect bobbin insertion or tension imbalance. Regular maintenance—clean bobbin area, replace worn threads, and use compatible thread weights—helps ensure consistent stitching.