Underthreads

Traditionally, synthetic underthreads (polyester and nylon) were used with synthetic top threads and natural underthread (cotton) with natural top thread.

However, there is now a tendency towards synthetic underthreads, which are not as fluffy as cotton, to be used with natural and synthetic top threads.

The pre-wound bobbins allow all heads on a multihead machine to be loaded with bobbins of the same length. Although differing thread tensions may mean some heads have a small amount of underthread left, it is still more cost effective to throw these away and load the whole machine again. This way, the machine only stops each time all the underthreads need replenishing, saving valuable time.