Topstitching thread is a thick, heavy polyester thread that is used when heavy duty sewing is required. It is good for heavy furs or leather and requires a special needle. Sliver is a thin, flat, ribbon-like polyester film that is metalized with aluminum to make it brilliant and reflective. A specialty needle is required. Wash-Away thread is strong enough to hold a garment together for fitting and then washes away with water.
Woolly nylon is a stretch thread made of texturized nylon or polyester.
It is used on a serger for a decorative finish or where stretch seams are desirable. Many of these threads can be used on both the sewing machine or serger. Experiment a little and discover some new uses for these exquisite specialty threads. Your fabric will influence the type of thread you select as well as its fiber content. Fiber content of your thread need not be the same as your fabric.