Introduction:
In
sewing, a seam is the join where two or more layers of fabric, leather, or
other materials are held together with stitches. Seams in modern mass-produced
apparel, footwear, house hold textiles and sporting goods are sewn by
industrial sewing machines. Home shoe making, dressmaking, quilting, crafts,
haute couture and tailoring may use a combination of hand and machine sewing.
In
clothing construction, seams are classified by their type (plain, lapped,
bound, flat) and position in the finished garment (center back seam, inseam,
side seam). Seams are finished with a variety of techniques to prevent raveling
of raw fabric edges and to neaten the inside of garments.
Seams
used for assembling sewn products are load bearing and ideally should be
similar in physical properties to the material being sewn. The stitch type and
sewing thread used will vary with each application. Hence, it is important to
be familiar with various seam types, their applications and variations
available so that you can choose the right seam to suit your sewing
needs.
Seam Classification:
Seams
are classified according to the type / number of components used. There are
eight classes of seams defined as per ISO 4916:1991.
In
the past, seams were described as Flat, Superimposed, Lapped or Bound.
Stitching (then differentiated from seams) were described as Edge finishing or
ornamental. Varieties of seams are illustrated below together with their
descriptions under the above and the new system.
Seam Classes:
Class
1 - Superimposed seam
Class
2 - Lapped seam
Class
3 - Bound seams
Class
4 - Flat seams
Class
5 - Decorative / Ornamental stitching
Class
6 - Edge finishing / neatening
Class
7 - Attaching of separate items
Class
8 - Single ply construction
Class
1 - Superimposed seam(s)
These
generally start with two or more pieces of material superimposed over each
other and joined near an edge, with one or more rows of stitches. There are
various types of seams within this class.
Stitches
Used
A
superimposed seam can be sewn with Stitch Types 301 or 401 to create a simple
seam. The same seam type can also be sewn with Stitch class 500 (Over edge
stitch) or Combination stitches (e.g., Stitch class 516)
Application
used
to create neat load bearing seams for lingerie, shirts, etc.
Class
2 - Lapped seam(s)
In
this class of seam, two or more piles of material are lapped (i.e., with edges
overlaid, plain or folded) and joined with one or more rows of stitches.
One
of the most popular of this class is the Lap felled type, involving only one
stitching operation - a strong seam with fabric edges commonly used to protect
jeans or similar garments from fraying. The superficially similar French seam
type involves two stitching operations with an intervening folding operation -
a flat, folded seam with only one row of stitching visible on the top surface.
This
seam class consists of a minimum of two components and can have different
varieties consisting of a number of rows of stitching.
Stitches
Used
The
lap felled seam is generally sewn with a 401 chain stitch
Application
The
looped seam is the most commonly used seam. It is used in jeans manufacture
because of its strong construction. The French seam is commonly used for rain
wear, and edge stitching front facings on jackets and dresses
Class
3 - Bound seam(s)
These
are formed by folding a binding strip over the edge of the piles of material
and joining both edges of the binding to the material with one or more rows of
stitching. This produces a neat edge on a seam exposed to view or to wear.
There are a variety of bound seams.
Stitches
Used
401
chain stich or 301 lockstitches
Application
Necklines
of t-shirts
Class
4 - Flat seam(s)
In
these seams (sometimes called Butt seams), two fabric edges, flat or folded,
are brought together and over sewn with stitches.
The
purpose of these seams is to produce a joint where no extra thickness of fabric
can be tolerated at the seam, as in underwear or foundation garments. The
looper thread(s) must be soft, yet strong and the cover thread may be
decorative as well as strong. This seam is referred to as a flat seam because
the edges do not overlap one another, they will be butted together.
Stitches
Used
Zigzag
lock stitch, chain stitch or covering stitch (class 600)
Application
This
type of seam will consist of two components and can be seen on very fine
knitted garments where seams are required to be free from bulk
Class
5 - Decorative / Ornamental stitching
The
ornamental stitch is a series of stitches along a straight or curved line or
following an ornamental design, on a single ply of material. More complex types
include various forms of piping, producing a raised line along the fabric
surface.
Application
The
stitching results in decorative surface effects on the fabric e.g., pin tucks,
application of braids, etc. This seam type consists of a minimum of one
component
Class
6 - Edge finishing / neatening
Edge
finishing stitch is where the edge of a single ply of material is folded or
covered with a stitch. The simplest of these operations is Surging, Type
6.01.01, in which a cut edge of a single ply is reinforced by over edge
stitching to neaten and prevent fraying. The seam class must include seams
whereby the edges are neatened by means of stitches and can be used in cases
where the raw edge requires finishing. There is only ever one component to this
type of seam. This includes other popular methods of producing a neat edge like
hemming and blind stitch hemming.
Application
Surging
trouser panels, fly’s, facings, etc.
Class
7 - Attaching of Separate Items
This
seam class involves seams that require the addition of another component onto
the edge of a piece of fabric e.g., elastic braid onto the edge of ladies
briefs. This type of seam requires two components.
Class
8 - Single Ply Construction
This
seam class consists of one piece of fabric that is turned in on both edges. It
is most commonly seen in belt loops or bets for which a folder can be attached
to the machine. This type of seam requires only one component.