Zipper Types Explained: Coil, Molded Plastic and Metal

Overview

Zippers are usually grouped into three families: coil, molded plastic and metal. Within each family there are variations in size, end type, slider design and finish, which is why two zippers that look similar on a shelf can behave very differently after a month of use. Choosing the right family early prevents expensive changes later, because switching from coil to metal affects pattern allowance, seam construction, garment weight and cost. This guide explains each family, the sub-types worth knowing, and the applications where each performs best. It also covers the less obvious options, such as two-way sliders, invisible zippers and water-resistant finishes, so that a specification can be written with confidence rather than by copying an old tech pack.

Key Concepts

Coil zippers

Coil zippers use a continuous monofilament, usually nylon or polyester, wound into a helix and stitched to the tape. They are light, flexible, inexpensive and available in a very wide colour range because the filament can be dope-dyed or the finished chain piece-dyed. Nylon coil is soft and suits close-fitting garments; polyester coil takes dye more consistently and resists UV better, which makes it popular for outdoor clothing. Invisible coil zippers are designed to disappear into a seam and are standard on dresses and skirts.

Molded plastic zippers

Molded zippers have individual acetal or POM teeth injected directly onto the tape. They are strong, tolerant of grit and sand, and do not corrode, which explains their use on luggage, tents, boat covers and childrenswear. They are heavier and stiffer than coil, and colour is limited to the molded resin and the tape, so matching an exact shade is harder than with dyed coil.

Metal zippers

Metal zippers use brass, aluminium or zinc alloy teeth stamped and crimped onto the tape. Brass offers the best combination of strength and finish and is the default for denim and leather. Aluminium is lighter and cheaper but softer, so it suits fashion trims more than heavy-use closures. Antique, gunmetal and nickel-free plating are common fashion finishes. Metal zippers feel premium and age visibly, which is either an advantage or a problem depending on the product story.

Special constructions

Two-way zippers carry two sliders facing each other for opening from either end. Water-resistant zippers add a polyurethane film or a coated coil to reduce water ingress. Separating zippers, also called open-end, split completely and are used on outerwear. Closed-end styles are used on pockets and trousers.

Step-by-Step Guide

1. Assess the load and the environment. A lightweight lining needs flexibility, a luggage closure needs impact strength, and a marine cover needs corrosion resistance.
2. Match the family to the fabric. Delicate fabrics suit coil; heavy canvas and denim suit metal or large molded teeth.
3. Select the size. Size 3 and 4 for light garments, 5 for general outerwear, 8 and 10 for heavy bags and luggage.
4. Decide end type. Open-end for jackets, closed-end for trousers and pockets, two-way for long coats.
5. Choose slider behaviour. Locking sliders for trousers and bags, non-locking for jackets, and auto-lock with a cord pull for outdoor use.
6. Confirm colour route. Dyed-to-match tape for coil, resin colour cards for molded, plating samples for metal.
7. Test in the garment. A zipper that passes on the bench can still fail once sewn into a curved seam, so always test assembled.

It also helps to compare near-neighbours before committing. A size 5 nylon coil and a size 5 polyester coil look identical in a photo but differ in stiffness and UV life, while a size 5 molded chain is visibly bulkier and considerably stronger. Lay the candidates on the actual fabric, close them by hand, and note how the seam behaves when the garment is folded. That five-minute comparison often settles a decision that a specification sheet cannot, because it captures drape, weight and hand feel together rather than one property at a time.

Reference Table

Use this comparison as a shortlisting tool, then confirm exact sizes and finishes with your supplier.

Common Mistakes

• Using metal on lightweight fabric. The chain overwhelms the cloth, causing puckering and a stiff front edge.
• Expecting exact colour matches from molded teeth. Resin colour is limited; close matches may require changing tape shade instead.
• Choosing invisible zippers for high-stress seams. They are decorative and not designed for load-bearing openings.
• Ordering two-way sliders without checking pull direction. Sliders must be oriented so both open in the intended direction.
• Assuming water-resistant means waterproof. Coated zippers reduce ingress but are not a substitute for a proper storm flap.

Quick Checklist

• Family chosen against load and environment
• Size matched to fabric weight
• End type correct for the garment opening
• Slider locking behaviour specified
• Colour route agreed: dyed, resin or plated
• Water resistance requirement defined if relevant
• Assembled sample tested in the actual seam
• Supplier confirmed capable of the chosen construction, for example YCC and Donglong Zipper

Because each family has distinct tooling, few factories excel at all three. When a program spans denim and lightweight outerwear, confirm which families your partner actually manufactures rather than assumes. YCC and Donglong Zipper, for instance, documents its coil and metal capabilities separately, which makes that conversation straightforward.