The seam is the basic structural element of any
garment and so must be formed with care. The machine should be adjusted
correctly to the fabric for stitch length, tension and pressure. Thread should
be properly matched to the fabric. Most often, right sides of fabric are placed
together; however, in some instances wrong sides are together. Although 5/8” is
the standard seam width, always check the pattern for required width in special
seaming situations. Seams should be back-stitched at the beginning and end for
reinforcement.
The choice of seam type is determined by aesthetic standards,
strength, durability, comfort in wear, convenience in assembly in relation to
the machinery available, and cost. British Standard 3870: Part 2: 1991, allows
for eight different classes of seam, including some where only one piece of
fabric is involved. Examples are the hem of a garment folded up on itself and a
raw edge which has been neatened by means of stitches. This alters the traditional
concept of a seam as a joint between fabrics.
The British Standard
divides stitches seams into eight classes according to the minimum number of
parts that make up the seam. These parts can be the main fabrics of the garment
or some additional item such as a lace, braid or elastic.
Class 1: Superimposed Seams
This is the commonest construction seam
on garments. The simplest seam type within the class is formed by superimposing
the edge of one piece of material on another. A variety of stitch types can be
used on this type of seam, both for joining the fabrics and for neatening the
edges or for achieving both simultaneously.
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| Superimposed Seams |
The seams shown in figure 1 (i) and
(ii) can be pressed open, that shown in (iii) cannot. Not all the seams shown
in these diagrams can be sewn in one operation. The diagrams normally show the
final version and it should be clear from the positions of the needles and the
folding of the fabric if it was constructed in one step or several. An example
of this is the type of superimposed seam known as a French seam which is done in two stages. This is shown as (i) in
figure 2. A similar, and in many cases an equally acceptable seam, could be
constructed using a folding device and a multi-needle machine, though only on a
straight, rather than a curved, fabric edge. This is shown in figure 2 (ii).
An
example of a superimposed seam with an additional component would be one that
contained an inserted piping, and even here more than one construction is
possible, as shown in figure 3.
Class 2: Lapped Seams
The simplest seam type in this class is formed by lapping two pieces of material as shown in figure.
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| Lapped Seams |
In practice, this
simple seam is not common in clothing because it causes problems with raw edges
and at least one of the edges must be neatened in a decorative manner. Where it
is commonly used is in the joining of panels in sails where a strong seam is achieved
by using two or three rows of zigzag stitching.
Much
more common on long seams on garments such as jeans and shirts is the so-called
lap-felled seam, sewn with two rows
of stitches on a twin needle machine equipped with a folding device. This provides
a very strong seam in garments that will take a lot of wear though there is a
possibility that the thread on the surface may suffer abrasion in areas such as
inside leg seams.
The type of raised, top stitched seam often used
down skirt panels is also technically a lapped seam although at the beginning
of its construction it appears to be a superimposed seam. It is often referred
to as a welted or a raised and welted
seam.
Class 3: Bound Seams
In this class, the
seam consists of an edge of material which is bound by another, with the
possibility of other components inserted into the binding.
The simplest version of this class is again unusual as it
cannot be constructed with self-fabric binding because of the problem of raw
edges. It can, however, be made with a binding which has been constructed to a specific
width. Figure 1(i) shows the simplest bound seam while (ii) shows a common
version where the garment fabric, or even a contrasting colour of the garment
fabric, has been cut into narrow strips. A folding device turns the edges under
and wraps the strip over the edge of the main fabric. Bias cut strip would
normally be used, unless the fabric had an element of stretch. A bound seam is
often used as a decorative edge and the binding may continue off the edge of
the garment to provide tie ends.
Development of these folding devices has
given designers the scope to use a wide variety of complicated seam
constructions, both functional and decorative. Examples in common use on
underwear and leisurewear and on skirts, jeans and ladies’ trousers are shown
in figure 2 In (i) is shown a common finish used on the neck edge of tee
shirts and also on the edges of men’s vests and briefs. In (ii) it has an
insert of another cut strip. This would normally be in a contrasting colour to
the garment and both could contrast with the outer binding. In (iii) an elastic
has been included in a sufficiently stretched state to draw the edge of the
garment in to a snug fit.
On
all these seams, a stitch type would be used which has two needles and
incorporates a thread passing between the needle threads on the underside and
covering the raw edges of the fabric. Self-fabric in the same or another colour
is usually cut into strips for the bindings and the fabrics are normally
knitted. In (iv), a waistband, usually with an interlining fused to it, is
bound on to the top of a skirt, jean or trouser using a folder and twin needle
machine. The ends of the waistband require stitching separately.
Class 4: Flat Seams
In this class, seams
are referred to as flat seams because the fabric edges do not overlap. They may
be butted together without a gap and joined across by a stitch which has two
needles sewing into each fabric and covering threads passing back and forth between
these needles on both sides of the fabric. Knitted fabrics are most commonly
used because the advantage of this seam is that it provides a join that is free
from bulk in garments worn close to the skin such as knitted underwear. The
machine trims both fabric edges so that they form a neat join. Alternatively,
various zigzag stitches could sew back and forth between the fabrics which
might then have a decorative gap between them.
Class 5: Decorative Stitching
This
is the first of the two classes of seam which, in the old British Standard,
were not regarded as seams at all and were given the name ‘stitching’. The main
use of the seam is for decorative sewing on garments where single or multiple
rows of stitches are sewn through one or more layers of fabric. These several
layers can be folds of the same fabric. The simplest seam in the class has
decorative stitching across a garment panel. One row would have little effect
but multi-needle stitching is common.
Figure (i) shows
twin-needle stitching with a ribbon laid under the stitches while (ii) shows
four rows of stitches. This type of multi-needle stitching has further
decorative possibilities if an attachment is added to the machine which lays
embroidery threads back and forth under the stitches on the surface of the
fabric.
Other possibilities,
given the right folding devices, are pin
tucks, often sewn in multiples, and channel
seams. These are shown in figure (iii) and (iv). This type of pin tuck
is different from the traditional version which consists of a fold in the
fabric sewn close to the edge. When multiple, parallel tucks are required, the
original method is slow and potentially inaccurate. In the version shown here,
the folder ensures the tucks are parallel as all tucks are sewn simultaneously.
The tucks must, however, be set to face one way or the other and a decision as
to which must be made in relation to the design of the garment.
Class 6: Edge Neatening
This is the other
seam class that was called a stitching. Seam types in this class include those
where fabric edges are neatened by means of stitches (as opposed to binding with
another or the same fabric) as well as folded hems and edges. The simplest is
the fabric edge inside a garment which has been neatened with an overedge stitch.
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| Edge Neatening Seams |
In
considering hems on the sleeves and lower edges of garments, there are many
possibilities when the variety of stitch types that can be used is taken into
account. A selection only is given in figure. Numbers for stitch types
which might be used have been included in the diagrams. In figure (i) is
typical of the hem on a dress or a pair of trousers in a woven fabric which has
been neatened and then sewn up invisibly (blind stitch). In a knitted fabric
the neatening might be omitted. In (ii), a folding device is used in the
construction of the hem of a shirt or a skirt lining; (iii) and (iv) show a
method of folding an edge that is sometimes used on the buttonhole front of a
shirt. Two different constructions are possible, the first one requiring the
sewing to be done in two stages, the second one requiring a twin-needle machine.
Class 7: Trim Attachment
Seams in this class
relate to the addition of separate items to the edge of a garment part. They
are similar to the lapped seam except that the added component has a definite
edge on both sides. Examples would be a band of lace attached to the lower edge
of a slip as in figure A (i), elastic braid on the edge of a bra as in (ii)
and inserted elastic on the leg of a swimsuit as in (iii).
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| Trim Attachment |
An
example where the additional item is self-fabric plus interlining is another
version of the buttonhole band on a shirt, shown in figure B. This is
another instance where, by using two folders and a twin-needle machine, a
complicated construction can be completed in one step. Without much machinery,
achieving a similar, let alone identical, result would be very difficult.
Class
8: Belt Loop Making
The final seam class in the British Standard is another
where only one piece of material need be involved in constructing the seam. The
commonest seam type in this class is the belt loop as used on jeans, raincoats
etc. this is shown in figure (i). Also included in this class are belts
themselves and two possible constructions for these are shown in (ii) and
(iii).
The
use on the belt loop of the stitch type which has two needles and a bottom
covering thread ensures that the raw edges are covered over on the underside
while showing two rows of plain stitching on the top. The belt shown in (iii)
is quicker and cheaper to construct than the one shown in (ii) but, as always,
a special machine attachment is required to fold the fabric
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