Sewing Thread Quality: The 10 Requirements

A stitch is only as good as the thread forming it. A quality sewing thread has to survive high-speed sewing, then washing, wear, and cleaning for the life of the garment. Ten properties define a good thread, and each one prevents a specific failure.

The ten requirements

#	Property	Prevents
1	Good tensile strength	Seam failure in wash and wear
2	Smooth, fault-free surface	Needle friction, poor sewability
3	Uniform thickness/diameter	Knots and needle-eye jamming
4	Good elasticity	Weak, poor-quality seams
5	Low shrinkage	Seam puckering
6	Chemical resistance	Damage in wash/bleach/dry-clean
7	Abrasion resistance	Premature wear, breakage
8	Colour fastness	Running/fading colour
9	Minimal metamerism	Shade mismatch under different light
10	Proper lubrication	Friction and needle-heat damage

The detail that matters

Tensile strength (1) holds the seam secure through wash and wear.
Smooth surface (2) cuts friction between needle and material at high speed; the thread must be well lubricated for sewability and abrasion resistance.
Uniform diameter (3) lets the thread move smoothly through the needle eye; an uneven thread twists into short knots and jams at the eye.
Elasticity (4) recovers the thread's length once tension releases, driving seam strength and finish.
Low shrinkage (5) matters most on higher-shrinkage fabric, mismatched shrinkage is what causes seam puckering.
Colour fastness (8) is tested against chlorinated water, perspiration, cold-water staining, dry cleaning, wet/dry pressing, and bleaching.
Metamerism (9) is when the same thread colour looks different under different lights; assess shade in a colour-matching cabinet with standard illuminants.
Lubrication (10) reduces friction and protects from needle heat, and must be non-staining, non-soiling, and neutral to thread colour.