If your sewing has been going wrong in ways that don’t make sense (skipped stitches, seams popping, thread fraying through the bobbin), it’s worth checking the thread before you blame your machine. Cheap or inconsistent thread causes all sorts of problems. It builds up lint in your tension discs, breaks under speed, and shifts in quality from one end of the spool to the other. You can spend an hour re-threading, swapping needles and fiddling with tension without realising the spool itself is the issue.

Good thread isn’t just about colour. It needs to cope with heat when you sew fast or press a seam. It needs to stretch with the fabric if the fabric stretches. It needs to sit softly in the seam instead of feeling wiry against the skin. And it needs to behave the same way after you wash the garment. One thread won’t do every job, but a couple of reliable options will cover most things.

Metrosene: the best all-purpose thread for garment sewing

Metrosene is Mettler’s everyday workhorse. It’s a 100% polyester thread tested at roughly 20% stronger than many standard sewing threads, and it handles heat well (which matters once you’re sewing at speed or pressing a finished seam). It’s the thread most of us want sitting in the machine for woven dresses, tops, and anything that gets washed constantly.

It comes in 318 colours across 150m spools, so colour matching is actually possible rather than picking the “close enough” navy and hoping for the best. You can also use it for quilting, embroidery, or in your overlocker if you need to.

Quick tip on overlocker threads: you don’t have to buy four full spools of the same colour. Load three bobbins onto your overlocker and keep one main spool going, or swap just the left needle thread to match your fabric so the stitching doesn’t show through on the right side.

Seraflex: the best thread for stretch fabric without a coverstitch

This is the one for anyone sewing knits who doesn’t own a coverstitch. Twin needles can work but they’re fiddly. Zigzag can look messy. A plain straight stitch on stretch fabric snaps the second you pull the garment on.

Seraflex is made from a fibre called PTT, which gives it up to 65% elongation. That means a straight stitch behaves like a stretch stitch. You can topstitch a knit hem, stitch a neckband, or finish a hood without any of the usual stretch-fabric drama. In the video I compare a straight stitch sewn with regular thread (snaps on the first pull) against the same stitch sewn with Seraflex (holds beautifully, no breakage, no visible stress on the seam).

One thing worth knowing: when you wind Seraflex onto a bobbin, reduce the bobbin winder tension or hand-wind it. If it goes on too tight, you’ll overstretch the thread and lose the stretch properties once it’s sewn. You can use Seraflex in the bobbin (I keep Metrosene in mine for everyday sewing), but if you do, be gentle with that winding step.

Seraflex comes in 72 colours across 130m spools. It’s a small upgrade that makes a big difference to how wearable a knit garment is after the first wash.