Thread And Seam Construction

THREAD & SEAM CONSTRUCTION

BY MACKENZIE WALTONMARCH 2012

• Thread sizing conventions

• Common types of sewing thread

THREAD BASICS

Thread size is determined the same way that yarn size is determined for textiles. While there are different systems, they are all based on weight and length specifications, and not by diameter as might be assumed.

• METRIC TICKET (Nm) # of 1,000 metre lengths in 1,000 grams

• COTTON COUNT (Ne) # of 840 yard hanks in 1 pound• TEX grams per 10,000 metres

• DENIER grams per 9,000 metres

Thread Size

Thread Size

Thread Size

GENERAL GUIDELINES FOR THREAD SIZE SELECTION

SEWING THREAD SIZES BY TEX

FABRIC WEIGHT (GSM)

FABRIC WEIGHT (oz/yd2) GARMENT EXAMPLES

18, 24 65 - 140 2 - 4 T-shirts, Lingerie

24, 27, 30 140 - 200 4 - 6 Shirts, Dresses

30, 40 200 - 275 6 - 8 Light-Weight Bottoms

40, 60 275 - 400 8 - 12 Light-Weight Denim

60, 80, 105 400 - 500 12 - 15 Heavy-Weight Denim

COTTON THREAD

Generally provides good sewing performance but strength and abrasion resistance is inferior to synthetic threads of equal thickness

• Mostly used for piece-dye items• Shrinkage may cause puckering after wash/dye• Can be mercerized – reduces shrinkage, increases

strength and luster, improves dye up-take

Common thread types

COTTON THREAD

MERCERIZATION

Common thread types

SPUN POLYESTER THREAD

Made with staple polyester fibers. Provides good sewing performance, good dimensional stability and good stitch locking properties due to the fibrous surface.• Resistant to sunlight and chemicals• Stronger than cotton, including 4X better abrasion

resistance• Ideal for light to medium weight fabrics

Common thread types

CORESPUN POLYESTER THREAD

Made by spinning staple polyester or cotton fibers around a continuous filament polyester core. Provides enhanced strength and elongation while maintaining stitch locking ability and can be run at higher speeds without breakages.• Higher machine speeds mean an increase in

productivity by up to 21%• Best thread for heavy fabrics, like denim and outerwear• More consistent sewing quality due to better loop

formation and resistance to damage• Most expensive general purpose sewing thread

Common thread types

TEXTURED FILAMENT THREAD

Continuous filaments of polyester or nylon are entangled by various methods to create softness and bulk. Ideal for overlocking and the looper of coverseams, these threads provide excellent coverage for raw edges• Most economical thread• Softness makes it ideal for lopping threads that sit close

to the skin• Excellent elasticity for stretch fabric applications• Often found in intimates, baby clothes, and athletic

wear

Common thread types

OTHER THREAD TYPES

• Mono-filament ‘Invisible’ Thread• Embroidery Thread• Elastic Thread• Specialty – Lurex, Indigo• Locked Filament Thread• Glow in the Dark

Common thread types

LUBRICATION

Regardless of construction, all threads are finished with a lubricating coating. This facilitates the passage of the thread through the machine and needles, reducing friction and heat that can cause damage.

LIFE SPAN

Under optimal conditions, thread will last about 18 months before the lubricants start to break down and thread quality starts to deteriorate. Unsurprisingly, most factories do not store thread in optimal conditions and so this period is usually much shorter.

Common thread types

• Needle sizing conventions

• Different Needle Types

NEEDLE BASICS

Needle Sizing

Most sewing is done with rounded-point needles. Actual cutting points are only used for leather and similar fabrics. ‘SetPoints’ are normal, lightly rounded points used for wovens, while knits demand more rounded needles, referred to as ‘ball points’

Different levels of roundness are identified with letter markers

Needle Types

R = Normal round• for light woven fabrics

SPI = Acute round• For densely woven fabrics

SES = Light Ball• Fine to medium knits, fine denim, medium to heavy

wovens

SUK = Medium Ball• Stonewashed denims, corsetry

SKF = Heavy Ball• Fine elastic materials, coarse knits

SKL = Special Ball• Medium to coarse elastic materials, coarse knits, lycra

Needle Types

The fabric and end use will determine the thread size and type, and needle type that you will use. The chosen thread will determine the needle size. There will be a range of possible thread sizes and types that can be used with any given fabric, depending on the application.

Needle-Thread Pairing

• Seam Types

• Stitch Types

• Applications

• What makes a good seam

SEAM CONSTRUCTION

• Superimposed Seams (basic simple seam)

• Lapped Seams • Lapped felled seams

• Flat Seams

• Bound seams

• Edge finishing

Seam Types

SUPERIMPOSED SEAMS

STANDARD SEAM FRENCH SEAM

Seam Types

LAPPED SEAMS

LAPPED SEAM

FELLED SEAM

Seam Types

FLAT SEAMS

Seam Types

BOUND SEAMS

Seam Types

EDGE FINISHING

Seam Types

301 - LOCKSTITCH

• Basic 1-needle straight stitch• Uses least amount of thread• Tightest and most secure stitch• High abrasion resistance due to low profile on

the fabric• No stretch

Stitch Types

304 - ZIGZAG

• 1-needle zigzag lockstitch• Can stretch, and can provide edge coverage• Used to apply lace or appliques• Used for bar tacks and button holes

Stitch Types

101 - CHAINSTITCH

• Formed using 1 thread only – no bobbin or looper

• On its own it is only suitable as a basting stitch• Blind hemming is a variation of this stitch

Stitch Types

401 - CHAINSTITCH

• Formed using 2 threads – needle and looper• Appears the same as 401, but is much more

secure and durable• Ability to stretch• Excellent for setting elastic• Frequently used for topstitching and for lapped

seams on high-wear garments like denim• Less thread passes through the fabric than on

a lockstitch, which can reduce seam pucker• 404 – Zigzag chainstitch

Stitch Types

406 and 407 – COVER STITCH

• 406 uses 3 threads, 407 uses 4• Excellent stretch. 407 has the most stretch• Excellent strength• Looper stitches are more efficient because you

don’t have to change a bobbin• Less thread passes through the fabric than on

a lockstitch, which can reduce seam pucker• Increased seam bulk• Increased cost

Stitch Types

503 – 2-THREAD OVEREDGE SERGE

• Formed using 1 needle and 1 looper thread• No structural strength – only suitable for

coverage of inner seam allowances

504 – 3-THREAD OVEREDGE SERGE (OVERLOCK)

• Formed using 1 needle thread, 1 looper thread, and 1 cover thread

• Most common for overlocking, and often used for sewing seams on knit fabric

Stitch Types

512 and 514 – MOCK SAFETY STITCH

• Formed using 2 needle threads, 1 looper, and 1 cover thread

• Common for seaming knits, and can be used for wovens as well

• Only 514 should be used on knits as it has better stretch

Stitch Types

515, 516 – SAFETY STITCHES

• A combination of an overedge stitch with a 401 chainstitch

• 515: 4-thread safety uses a 503 overedge serge

• 516: 5-thread safety uses a 504 overlock stitch

Stitch Types

FLATLOCK – 600 CLASS

• Formed using 2 – 4 needle threads plus 1 looper thread and 1 cover thread

• Fabric edges butt together but do not overlap• Highly elastic seams with very low profile for

maximum comfort• Efficient to sew• Very high thread consumption• Common for performance and scuba wear

Stitch Types

SPECIALTY STITCHES

• Pick Stitch - classic• Pick Stitch – on knits

Stitch Types

SPECIALTY STITCHES

• Whip Stitch• Blanket Stitch (single buttonhole)

Stitch Types

• Tension• SPI• Thread Choice• Stitch Choice• Needle Type• Needle Condition• Seam Width• Additional Elements

Elements of a Good Seam

SEAM PROBLEMS

• Seam Pucker• Grinning• Skipped Stitches• Broken Needle Threads• Broken Bobbin Threads• Needle Damage on Fabric• Seam Slippage

Trouble Shooting

SEAM PUCKER

• Bad tension• Bad feed• Fabric-Thread instability

• Uneven shrinkage during finishing• Thread-bloat from washing

• Structural jamming/Inherent pucker• Tight weaving does not have enough room

between yarns for thread• Sewing caused yarns to be pushed out of place

Trouble Shooting