Threads have come a long way since the caveman was sewing hide and fur together with fine strips of animal hide. The first uses of thread were to create woven tapestries from wool yarn and then seamstresses began to use the same material to create garments
Cotton thread is the most popular, and made from cotton fibres. It’s soft and won’t stretch. This thread has a low in lustre but can fade and shrink. High quality cotton threads are made from the long cotton fibres, these tend to be stronger and less likely to fray in your machine. You can buy mercerized cotton-wrapped polyester threads (holds colour and lustre is better).
Use for: all-purpose sewing and dressmaking with medium fabrics
Polyester thread is man-made and tends to be extremely strong with a medium lustre. It’s also economical to buy and comes in a wide selection of colours, with the added benefit of not shrinking or fading.
Use for: quilting and light and medium weight fabrics, machine embroidery
Silk is made from the silk worms cocoons and is thinner and more elastic with a high lustre. It tends to sink into garments, when sewn which is good for hand embroidery and needlework.
Use for: seaming, topstitching, buttonholes and hand sewing
Rayon thread is also man-made and has a high-lustre. It’s soft, durable and available in a wide selection of colours. Rayon thread works well with high-speed sewing such as machine embroidery and doesn’t suffer from fraying or breaking.
Disadvantage is, its not heat resistant or colourfast
Nylon threads are synthetic, and although it is a very strong thread, the negatives of using can overweigh any positives. It's not colourfast nor heat resistant, and will deteriorate over time with washing.
Rule of thumb
A good thread should pass easily through the eye of a needle
You gets what you pay for!
Always choose a good quality thread over cheaper alternatives to ensure best results. If you look at cheaper threads under the microscope (if you have one handy…) you’ll find that they are not smooth and looked frayed and bumpy. If in doubt, stick to brands that you know or that have been recommended.
Make sure you match the thread’s fibre content to the fabric that you are using. For example, use natural fibre thread with natural fibre fabric and synthetic thread with man-made fabrics. Always use the same thread type in both the needle and bobbin.
Thread type can also affect the tension on your sewing machine. If you are using rayon thread, your tensions will have to be a little looser than for a polyester thread, which can stand a tighter tension to avoid looping.
Basting – Lightweight thread usually 100% cotton for temporary stitching
Invisible – Usually nylon, and used for mending and attaching trims where you don’t want to see stitching.
Machine embroidery – High gloss finer threads available in a wide selection of colours, textures and sizes. Often polyester or rayon and comes in plain, variegated and iridescent colours.
Metallic – These have a shimmer to them and are ideal for decorative stitching/machine embroidery.
Overlocker – Sold on cones especially for high speed overlocking.
Topstitching – Strong thread that produces a well defined stitch that is to be seen.
Bobbinfil – Designed for use with machine embroidery, it comes in black or white and forms the underside of heavily stitched embroidery preventing puckering.