An invisible zip has its coil on the back so that, once sewn, the closure looks like a plain seam with a small pull at the top; it is the standard choice for dresses, fitted skirts and anything where the closure should disappear. A regular zip has its teeth or coil on the front, is inserted centered or lapped after the seam is sewn, and is stronger, easier to replace and better on heavy fabric, which makes it the choice for trousers, jackets, bags and pouches. The sections below explain the differences, how each is sewn and which to pick.
| Feature | Invisible zip | Regular zip |
|---|---|---|
| Look when closed | A plain seam with a pull at the top | Teeth hidden by a lap or a centered seam, stitching visible |
| Coil or teeth | Nylon coil, rolled to the back of the tape | Nylon coil, molded plastic or metal teeth on the front |
| Inserted | Before the seam below it is sewn | After the seam is sewn and basted closed |
| Foot needed | Invisible zip foot (grooved) | Standard zip foot |
| Strength | Moderate; coil only | Higher; metal and molded teeth available |
| Fabrics | Light to medium wovens and stable knits | Light to heavy, including denim and canvas |
| Repair | Replace the whole zip | Replace the zip or the slider |
| Price tier | Entry-level to mid | Entry-level to mid; metal costs more |
What is the difference between an invisible and a regular zip?
An invisible zip is a nylon coil zip whose coil is rolled toward the back of the tape. When it is sewn in, the stitching runs right in the groove next to the coil, and the seam allowances of the garment close over it. Nothing shows on the outside except the teardrop pull. It is sold in lengths from about 20 to 60 cm (8 to 24 in) and in a limited range of colors, because the tape never shows.
A regular zip, also called a conventional or standard zip, has its coil or teeth on the front. It can be a nylon coil zip (light and flexible), a molded plastic zip (the chunky kind on jackets and bags) or a metal zip (jeans and heavy trousers). It comes closed-end, for skirts, trousers and pouches, or open-end (separating), for jackets. The garment seam is sewn and basted closed, the zip is placed behind it, and the stitching that holds it is visible on the outside, either as two rows on a centered zip or one row on a lapped zip.
How is an invisible zip inserted differently?
The order is reversed. The zip goes in while the seam is still open; the seam below it is sewn afterward, running up to meet the zip stitching. The coil has to be pressed flat first, with the iron on a synthetic setting, so that the grooved invisible zip foot can hold the coil upright and stitch right next to it. Each side is sewn from the top down with the zip open, then the slider is closed and the seam below is finished with a standard zip foot.
It sounds fiddly and it is, the first two times. After that it is faster than a regular zip because there is no basting, no topstitching and no lap to measure. The invisible zip guide walks through the order with the foot settings for a domestic machine.
A regular zip is inserted after the seam is sewn. The seam is closed with long basting stitches along the zip opening, pressed open, and the zip is pinned or taped face down over the allowances. For a centered zip you stitch a rectangle around it from the right side, 6 to 8 mm (1/4 to 5/16 in) from the seam. For a lapped zip, one side is stitched close to the coil and the other is covered by a flap of the seam allowance, stitched 1 cm (3/8 in) from the seam. Then the basting is pulled out. Both versions use a standard zip foot, which comes with nearly every machine.
Which zip is stronger?
A regular zip. Its coil or teeth face forward and take the strain head-on, and metal and molded-plastic versions handle the daily open-and-close of jeans, jackets and bags for years. The fabric lap or the centered seam also protects the teeth from catching.
An invisible zip is a fine nylon coil, and the stitching sits very close to it. On a snug-fitting garment that is pulled on over the hips, the strain on a long invisible zip at the point of most stress can pop the coil open or make the slider separate from it. Invisible zips are not made in metal or molded plastic. Keep them for garments that are not under heavy strain at the zip, and give a fitted garment enough ease that the zip is not doing the fitting.
Which fabrics suit each zip?
Invisible zips suit light to medium wovens: cotton lawn, poplin, linen, crepe, viscose, satin, lightweight wool. They also work on stable knits such as ponte and scuba, where a zip is sometimes needed at the back of a fitted dress. They struggle in bulky fabric, because the two seam allowances have to close neatly over the coil, and in fabric with a lot of texture, which the foot's groove drags against.
Regular zips go in anything from voile to canvas. On heavy fabric a lapped zip is the standard, since the lap covers the teeth and the one visible row of stitching sits comfortably through many layers. On denim and workwear a metal zip behind a fly front is the classic choice. On bags and zip pouches the teeth are on show and often chosen as a feature, in a contrasting color or in metal.
Can you use a regular zip on a dress?
Yes, and until the 1960s every dress had one, usually lapped at the left side seam or centered at the center back. A lapped zip in matching thread is discreet on most fabrics and is stronger than an invisible zip on a fitted bodice. The visible row of stitching is the only tell. If you want the closure to vanish, use the invisible zip; if you want the strongest closure on a garment you will pull over the hips, the regular zip is the safer choice.
The same logic applies to skirts. A pencil skirt in a stretch twill can take an invisible zip at the center back, which is the usual modern finish; the same skirt in heavy wool crepe is more comfortable with a lapped zip, which handles the thickness and the strain of sitting down.
Can an invisible zip be sewn as an exposed zip?
Not usually. An exposed zip is a design feature, where the teeth and tape are deliberately on show, and it is made with a regular zip, most often a metal or chunky plastic one, set into a faced opening. An invisible zip has nothing to show. If you like the look of exposed hardware, buy a regular zip in the color you want the teeth to be.
Which should you choose?
- Fitted dress, sheath, slip or skirt in a light or medium fabric: invisible zip at the center back or left side. Buy it 5 cm (2 in) longer than the opening; the excess is cut off below the seam.
- Dress or skirt in a heavy or textured fabric: lapped regular zip, with the lap facing the center back.
- Trousers with a fly front: regular zip, metal on denim and canvas, nylon coil on lighter fabric. Sewly's trousers are pull-on at launch; a fly front is on the roadmap.
- Jacket or hoodie that opens fully: open-end regular zip, molded plastic or metal, in the length of the front opening.
- Zip pouch, bag, cushion cover: regular zip, nylon coil for a cushion cover where it hides in a seam, molded plastic or metal where the teeth show on a bag.
- A beginner's first zip: a centered regular zip on a cushion cover or a pouch, with a standard zip foot. The invisible zip is the second one to learn, once you have a feel for the foot.
Whichever you choose, buy the zip before cutting the fabric. The notions list on a pattern gives the length, and Sewly's sewing guide lists the zip type and length for each garment and option so you can check before you shop. Match the color to the fabric for an invisible zip and either match or contrast on a regular one, and if you cannot find the exact length, buy longer and shorten it from the bottom.