A quick overview of stitch types

Written by:

Gloria McConnell – [TC]² Manager, Senior Industrial Engineer
with contributions from Jack Nienke – [TC]² Manager, Technical Support

With a global economy, it is important to have a universal standard for communicating construction requirements.  Seams and Stitches classifications began as a government response to the need for procurement starting in 1926.  The final government standard Federal Standard 751a, 1965, filled the requirements for many years and can still be downloaded free as a pdf file.  Today the stitch classification system can be found in ISO 4915.  The ISO defines and illustrates the requirements for each.  This article is an overview of the system.  

Many times one word can have multiple meanings even in the same language.  To understand the system we need to understand the terminology associated with it.  A “stitch” is defined as a formation of thread for the purpose of making a seam or stitching.  There are 8 classes of stitches recognized in the ISO standard.

 

Stitch classes

The 100’s class includes one thread chain stitches.  Each loop of thread is interlaced with the next loop and is easily raveled out.  Examples of how this stitch class is used in apparel include chain stitch button sewing, chain stitch button holes and single thread blind stitch applications.  The top and bottom sides have different appearances with the straight stitch above and the loops below.  A spreader is used to manipulate the needle thread.  Below is a side view of the Class 101 chain stitch.

 

 

Shown below: the face side and underside of the Class 101 chain stitch

   Shown below:  the underside and face side of the Class 103 blind stitch

 

The 200’s class originally only included hand stitching, but some can now be formed by machines.  The single thread passes from one side of the fabric to the other.  This is typically accomplished with a shuttle type needle with the eye in the middle.  The pick stitch or saddle stitch, used to outline the lapels of jackets, can be placed in this stitch classification.  A pick stitch is one in which the exposed thread length on the fabric face is no longer than the thread width.  Longer exposed thread lengths are saddle stitches.  In back stitches, stitch type 202 adjacent stitches share the same needle hole.

The 300’s class includes the lockstitch where two threads, typically a needle and bobbin thread, interlock.  Both sides have the same appearance with the interlacing point in the middle of the fabric.  The lockstitch will not ravel and can not be picked out without destroying one or both of the threads.  The 301 lockstitch with one needle thread and one bobbin thread, is commonly referred to as a plain stitch.  Examples include joining or topstitching wovens, setting pockets and hemming.  Because the stitch is not very elastic, if used on knits, when the fabric stretches, the stitches will pop.  The bobbin thread has to be replenished more often than the spools of thread used on chain stitches which requires more allowances built into the time standard. The needle thread passes through the eye many times before being laid in the fabric so the thread must have good ply integrity.  A core or spun thread is usually specified, never a texturized thread.  Shown below is the Class 301 lockstitch.  Shown below:  the side view of the Class 301 lock stitch and the face and underside of the Class 301 lockstitch.

 

 

The 400’s class includes multi thread chain stitches.  All stitches in this class are interconnected on the underside by thread from a single looper thread.  The two sides have different appearances.  The face side appears similar to the plain stitch, but loops are visible on the underside.  The 401 chain stitch, formed by one needle thread and one looper thread, is commonly used on top center plackets in dress shirt and the inseams and rise seams of pants.  The 406 cover stitch, formed by two needle threads and one looper thread, protects a previous seam from abrasion.  The 400 stitches are elastic and will ravel from the trailing end.  These stitches historically cannot be sewn in reverse.  Through the years various methods have been employed to lock the stitches in:  tack separately, condense ending stitches, and malformed overlapping hem stitches.  Newer technology allows the ending stitches to be formed in the opposite direction by an auxiliary looper.

 Shown below: the side view, face side and underside of the Class 401 chain stitch.

 

Shown below: the face side and underside of the Class 406 cover stitch.

 

The 500’s class includes variations of a chain stitch where at least one group of threads pass over the edge.  A clean seam is produced with a built in edge cutting device.  Common applications include over locking a single ply to prevent it from fraying and joining woven or knit fabrics. Often the stitches is class can be confusing because a variety of generic terms have been used, including serge, merrow, overcast, and overlock.

The 504 stitch is formed by one needle thread and two looper threads and is commonly used for joining knits or wovens.

 

Shown below: Class 504 Overlock stitch.

 

The 600’s class includes top and bottom cover stitches.  The stitches are formed by at least three thread systems – needles, upper and lower cover threads.  The 606 also has an independent looper.  Cover threads lie on the top surface, held in place by needle threads, interlaced on the back of the seam by looper threads with the two covers over raw edges.  Common applications include joining underwear, dancewear and swimwear.  Shown below:  the Class 607 top and bottom cover stitch.

 

 

The 700’s class is for a specialized lock stitch using a single thread.  The formation of a lockstitch requires that the needle thread loop be wrapped around a second thread loop, which is a bobbin in the 300’s class.  In this class there is a single thread system a continuous needle thread.  An under spool is automatically filled from the needle thread supply before starting each stitching sequence.  The needle thread interlaces with the bottom thread that has been wrapped around a reel.  This is a less common stitch classification applicable only to short length seams or stitching.  The first stitch has no loose ends and has been used in tacking and shank button sewing.

The 800’s class includes safety stitches.  They were originally part of the 500’s classification in Federal Standard 751a.  These stitches are similar to an over edge stitch but with additional chain stitch a few millimeters from the edge.  The additional chain stitch in a true safety stitch is produced at the same time but is independent of the over edge thread systems.  The additional chain stitch in a mock safety stitch is interdependent.  A single machine simultaneously sews two or more rows of stitches of different classes.  The 802 is a 5 thread safety stitch which is a combination of a 401 and a 504 stitch formation.  In the Federal standard 751a it was referred to as a 516.

 

Shown below:  The Class 802 (old classification 516) Safety Stitch

 

 

Other terminology includes the word “stitch” but is not a special class of stitches.  For example:  a blind stitch applies to a stitch that is not visible on one side of the fabric being sewn.  It can be made with different stitch classifications from the 100’s, 300’s. 400’s and even 500’s class.  Zig zag stitches can be formed in the 300 and 400 classes. 
Covering stitches can be made by 400 and 600 class stitches, although only the 600 class is classified as such.

Each type of stitch has a unique footprint, made with one revolution of the machine.  This foot print can be diagnosed by a trained mechanic to trouble shoot machine problems. Customer specifications should provide the required stitches per inch, thread size and type and tolerances so there is no ambiguity in how to produce garment.  It is recommended that apparel buyers and manufacturers use seam sketches with dimensional notations as a means of specifying their seam and stitch requirements in addition to using the classification system.

For a detailed listing of all stitch types reference ISO 4915.
 

 

About the author:

[TC]² is a premier provider of consulting services specializing in operations improvement for Brands, Retailers and Manufacturers of apparel.  They have been helping companies create more value for their customers by maximizing the effectiveness of their people and processes for 20 years.  Their experienced staff assists companies to lower operating costs and improve efficiencies.  To learn how [TC]² can assist your company, email Will Duncan in Cary, NC, USA at wduncan@tc2.com or Arturo Rodriguez in Guadalajara, MX at arodriguez@tc2.com.