Different Types of Stitches: A Technical Guide to ISO Stitch Classes

In the apparel industry, the quality of a garment is often judged by its smallest unit: the stitch. Selecting the incorrect stitch class can lead to seam failure, poor elasticity, or fabric damage. This guide categorizes the six essential stitch classes as defined by the ISO 4915 international standard.

The Three Methods of Stitch Formation

Before selecting a class, you must understand how the thread is manipulated:

• Intralooping: A single thread passing through its own loop (e.g., Class 100).

• Interlooping: A loop from one thread passes through a loop from another thread (e.g., Class 400).

• Interlacing: One thread passes over or around another thread, common in lockstitches (e.g., Class 300).

Intralooping

Technical Breakdown of Stitch Classes

Class 100: Single-Thread Chain Stitch

Formed by a single needle thread through intralooping.

• The Pro View: Cost-effective but insecure; if the thread tail is pulled, the entire seam unravels.

• Best Use Case: Temporary basting and button-sewing on budget garments.

Class 200: Hand Stitching (Simulated)

Mimics traditional hand sewing. In modern manufacturing, specialized "pick-stitch" machines use a double-pointed needle to achieve this.

• The Pro View: High-cost and slow, used purely for aesthetic "artisanal" value.

• Best Use Case: Luxury suit jackets and high-end outerwear lapels.

Class 300: Lockstitch (The Industry Standard)

Formed by a needle thread and a bobbin thread through interlacing.

• Expert Tip: It appears identical on both sides. While very secure, it has zero elasticity and will "snap" if used on high-stretch fabrics.

• Best Use Case: Standard woven shirts, pockets, and zippers.

Class 400: Multi-Thread Chain Stitch

Also known as the "Double Lock Stitch," it uses needle and looper threads.

• Expert Tip: Much stronger and more elastic than Class 300.

• Best Use Case: Side seams on denim jeans and heavy-duty workwear.

Class 500: Over-Edge (Serging)

Stitches that wrap around the fabric edge to prevent fraying.

• The Pro View: These machines usually include a knife to trim the fabric edge simultaneously.

• Best Use Case: Essential for knitted fabrics and activewear.

Class 600: Covering Chain Stitch (Flatlock)

Complex stitches using up to nine threads to create a completely flat seam.

• The Pro View: High thread consumption, but prevents skin irritation.

• Best Use Case: Base layers, yoga leggings, and high-performance underwear.

Quick Reference: Stitch Selection Table

Class	Type	Security	Elasticity	Primary Industry Use
100	Chain	Low	Low	Basting & Buttoning
200	Hand	Medium	Low	Luxury Finish
300	Lock	High	Low	Woven Garments
400	Multi-Chain	High	Medium	Denim & Workwear
500	Over-Edge	Medium	High	Knits & Finishing
600	Covering	High	Very High	Underwear & Gymwear