Correct Stitching for Invisible Zips


Opti Invisible Zip Products 
Invisible Zips Insertion Techniques 
Frequently Made Mistakes in Sewing Invisible Zips


This technical bulletin is a comprehensive guide to invisible zips including best practice insertion techniques, product information, standards and recommendations, plus frequently made mistakes in sewing invisible zips.

Opti Invisible Zip Products

Opti Invisible Zip Products
S43 (#2) S44 (#2) S54 (#4) S64 (#5)
Chain width 4mm 4mm 5mm 6mm
Tape type Polyester knitted tape Polyester woven tape Polyester woven tape Polyester woven tape
Main uses
  • Lightweight skirts
  • Lightweight dresses
  • Lightweight ladies trousers
  • Lightweight sportswear
  • Skirts
  • Dresses
  • Ladies trousers / slacks
  • Sportswear
  • Pockets and sleeves of down and wading jackets
  • Bedding
Suitable fabric weight <100 gr/m2, light fabrics, knitted or woven, without lycra <140 gr/m2, light fabrics, knitted or woven, without lycra 140 - 220 gr/m2, knitted or woven fabrics, with or without lycra >220 gr/m2, knitted or woven fabrics, with or without lycra
Standards Certified to Öko-Tex Standard 100, Class 1.
Standard, Class A Ultra light (BSI 3084) or Class ½(ASTM) Standard, Class B Light weight (BSI) or Class ½(ASTM) Standard, Class B Light weight (BSI) and Class 3 (ASTM)
Sewing grooved foot Article C4PAM Article C4PAM Article S5PAM Article FOOT270
Care Information Invisible zips are not recommended for use in heavy washed denim and leather garments.
  • Not suitable for the tensions that occur in the waist and hips side openings of the garments.
  • Care should be taken to allow room for slider running where cross seams and panel seams are forming multilayer fabric construction: - through the waistband style in trousers or skirts - in dresses with side seams/ruffles/layers or pleats joining at the seam position of the zip - where the pocket seam joins midway along the zip seam
  • Suitable for use in the side openings of waist and hip areas.
  • Can be used in waistband and panel seam areas with multi-layer fabric construction.
Can be used in garments made of fabrics with lycra. - To be preferred in garments made of fabrics with lycra - Can be used in bedding, avoiding sharp turns and corners

Invisible Zips Insertion Techniques

Invisible Zips Insertion Techniques
Concealed zip Concealed zip iron on Concealed zip correct foot Concealed zip sewing foot
1) A concealed zip gives an effective opening approximately 2.5cm less than its length. Thus for a 20cm opening a 23cm zip is required. 2) Do not iron. Heat or pressure can damage the teeth of the zip. 3) The correct grooved foot for invisible zips must be selected. The nose and the channels are there to help keep the teeth vertical while stitching. 4) The sewing foot should be centered properly by aligning the needle to the center fin.
 Concealed zip balanced feed dog Concealed zip align edge Concealed zip spiral teeth
5) A balanced feed dog should be selected to obtain optimum appearance of the seam. This feed type will allow uniform pressure to be applied to the fabric and the zip, regardless of which side of the zip is sewn. 6) Turn the zip with puller to the fabric and fully open it. Align the edge of the zip tape to the selvedge of the garment panel. 7) Unfold the spiral teeth to be at right angles to the tape and lower the channel of sewing foot over the spiral as shown, with the nose of the foot above the top stop.
Concealed zip back tack Concealed zip sew length Concealed zip correct stop Concealed zip in correct stop
8) Once the grooved foot is positioned, commence sewing, back tack for approximately 5mm to secure the end of the zip. 9) Sew along the length of the zip, repeating on both sides. Back tack for approximately 5mm. 10) The correct stop position is 2mm before hitting slider. 11) The incorrect stop position is when the sewing foot is hitting the slider.
Concealed zip half stop Concealed zip insertion seam Concealed zip bottom Concealed zip bottom tape
12) Use a half foot to close the seam below the zip. 13) Stitch as near as possible to the zip insertion seam, overlapping by 5mm, back tack to secure 14) Note that approximately 4 cm of the bottom of the zip will be unattached at this stage. The bottom tape extensions of the zip should be secured to the fabric on both sides. Otherwise seam failures are possible.
Our technical advisers are always at hand to offer the help and support needed.

Frequently Made Mistakes in Sewing Invisible Zips

Frequently Made Mistakes in Sewing Invisible Zips
We strongly recommend to use dedicated feet for invisible zips which always deliver the correct result.
Stitching problem Stitching problem Using half sewing foot can lead to incorrect stitching and the fabric getting caught in the path of the slider, thus dislodging it.
Stitching problem Stitching problem Care should be taken to not stitch through the zip’s teeth, to avoid slider jamming and damaging the tape.
Needle damage  Needle damage Not using proper grooved foot may lead to teeth damage by the needle.
Care should be taken at design stage when invisible zips cross side seams or go through the waistband
Materials in the path of the slider Material slider Stitching should allow room for slider to run with ease, especially where cross seams and panel seams are forming multi-layer fabric construction.
No loop cords or labels which may jam the slider.
Loose threads Loose thread Care should be taken to cut away all loose threads to prevent the slider from jam and failure.
Loose tape ends Loose tape ends Do not leave the zip tape ends loose. Fix them to the seam allowance.