Nylon coil is the most common zipper in the world and the easiest to specify badly: softness, dye method and heat tolerance vary more than the catalogue suggests. These six answers cover the choices that change how a nylon zipper performs.
Nylon Zipper FAQ
Nylon or POM coil: what is the difference?
Both are moulded coil zippers, but the polymer behaves differently. Nylon is softer, takes dye more evenly and drapes well, which suits dresses, lightweight jackets and garment-dyed styles. POM, often sold as Delrin, is stiffer, has a lower moisture absorption and resists chlorine and chemicals better, which suits swimwear, luggage and outdoor gear. Nylon can absorb 2-4% moisture, so a nylon zipper may change length slightly in humid storage, while POM stays dimensionally stable. Nylon softens earlier under heat, so a sublimation press can distort it; POM tolerates higher temperatures. The rule: nylon for drape and colour, POM for dimensional stability and chemical exposure. Neither is stronger in every direction, so match the polymer to the laundry and finishing process. If a programme mixes both polymers across styles, keep the care labels consistent so the customer does not treat a POM zipper like a nylon one.
What sizes and applications suit nylon zippers?
#3 is the workhorse for dresses, skirts, pockets and lightweight jackets; #4.5 and #5 cover outerwear, hoodies and mid-weight bags; #8 and #10 handle luggage, covers and heavy-duty applications. The size number approximates the closed chain width, so a #5 measures about 5 mm. Nylon is a good default for any garment that is washed frequently, because the coil flexes with the fabric and does not corrode. Avoid it where the teeth will be exposed to abrasion, such as a boot or a floor-contact bag, and where a crisp metal look is required. For stretch knits, use a #3 reverse coil; for a jacket front that carries load, #5. Match the tape width to the seam so the coil does not roll.
Why does the nylon coil curl or wave?
Curling comes from tape tension and storage, not from the coil itself. A tape wound under tension takes a set, especially in a cold warehouse, and the coil follows. Let the zipper relax for 24 hours at room temperature before sewing, or steam it lightly at 60°C to release the set. If the wave appears after sewing, the tape was stretched during attachment, so use a walking foot and sew from the top down without pulling. Check the tape shrinkage against the fabric, because a 2% difference on a 600 mm opening is 12 mm of excess. Store zippers rolled, not folded, and keep them out of direct sunlight. Never store zippers near a heater or a loading dock door. A coil that still curls after relaxation should be rejected, since it will pucker the seam in wear.
How do I match nylon zipper colour to fabric?
Decide the dye method first. Dope-dyed coil has the colour in the polymer, so it is uniform, fast to washing and consistent between lots, which suits large programmes. Piece-dyed coil is cheaper in small runs and can be matched closely, but lot-to-lot variation is larger. Ask for a Delta E of 1.0 or below against the fabric standard under D65 lighting, and check metamerism under a second light source, because a match that looks right in the office can shift in daylight. For garment-dyed styles, use a dyeable nylon so the zipper takes the bath colour, and accept that the final shade depends on the fabric. Approve a physical sample on the actual fabric, not a colour card, and keep the approved sample as the reference for bulk.
Can a nylon zipper be ironed or heat-pressed?
Only with care. Nylon softens well below the temperatures used for cotton pressing, so a hot iron will flatten the coil and glaze the tape. Keep the iron under about 110°C, use a press cloth, and never rest the iron on the teeth. For fusing and sublimation, protect the zipper with a silicone sheet and keep the press cycle short; if the process runs above 180°C for more than 20 seconds, specify a heat-stable slider or attach the zipper after pressing. POM coil tolerates slightly more heat but still deforms. Test a scrap through the actual process and check that the slider still grips and the coil returns to shape. A deformed coil cannot be repaired, only replaced, so the test is cheaper than the rework.
Which slider type should a nylon zipper use?
Match the lock to the function. Auto-lock for a jacket front or a bag flap that must stay closed; non-lock for a dress, pocket or any opening adjusted while worn; semi-lock for a vent or a two-way application; pin-lock for childrenswear. The slider must match the coil gauge exactly, and the body width should suit the tape, since a narrow slider on a wide tape leaves the pull standing away from the garment. For lightweight nylon, a #3 slider with a small pull keeps the profile low; for outerwear, a #5 slider with a cord pull is easier to use with gloves. Replace a worn slider rather than the whole zipper, and check that the new slider runs smoothly in both directions before crimping the top stop.
YCC and Donglong supply nylon and POM coil zippers in matched dye lots, with sliders selected for each garment's lock and pull requirement.