The overlock seam and where it belongs
Short answer: An overlock closes the fabric edge and can stretch. It is the standard seam in knit clothing, and it should look even on the inside.
What the overlock does
The overlock sews and finishes the edge in one motion. It closes the fabric edge so it does not fray, and it has enough thread to stretch with the fabric. Without it, knit fabric would curl and unravel at the edge over time.
Where it is used
In side seams, armholes and the crotch of almost all knit clothing, the overlock sits as standard. It is not entirely flat, so in underwear it is often combined with a flat seam where the fabric sits closest to the skin.
How to judge it
Turn the garment inside out and look at the thread. It should sit close and even without gaps, and the edge should be fully covered. See bamboo t-shirts for men.
The difference between three and four threads
An overlock can be sewn with three, four or more threads. More threads give a denser edge and more strength, while fewer threads are faster to sew but give a weaker seam that unravels more easily if a thread snaps.
How durable it is in practice
In everyday use, a good overlock lasts many years, provided the surrounding fabric does not wear out first. It is rarely the seam itself that gives out before the rest of the garment, unless it was sewn with too few stitches.
Combination with other seam types
A single garment often shows several seam types at once. Overlock at the sides, a flat seam at the crotch and a ribbed neckline is a common combination, where each seam type solves its own task best.
Bamboo clothing for women and men
The cut differs between women's and men's clothing, but the principle behind the overlock seam stays the same. See bamboo clothing for women and bamboo underwear for men for examples.
How to extend its life
Never cut loose threads off right away. Tie a small knot at the end, so the thread cannot unravel further and pull the overlock with it, which can otherwise ruin a whole seam quickly.
See it as part of the whole
A good overlock is part of an overall piece of sewing work. Combined with solid fabric and thoughtful construction, it gives a garment that survives daily wear and repeated washing without coming apart at the edges.
Frequently asked questions
Can overlock come undone
Yes, if a thread snaps it can unravel along the whole seam. Tie a knot at the end if you see a loose thread sticking out.
Is overlock worse than flatlock
No, it is stronger in many cases. Flatlock is flatter and more comfortable against the skin. They are typically used in different places on the same garment.
Why are there four threads
Four threads give both a seam and an edge finish at the same time. Three threads are faster to sew but often end up a bit weaker.
You can find the full range at Bamboo-Clothing.com.
