Hook-and-loop is a pair: a hook face and a loop face. Press them and hooks catch loops. Peel them and they let go. The brand name Velcro is a company, not a generic. On a tech pack write hook-and-loop (or touch fastener) and then the construction. “Velcro, black, 20 mm” is how you receive the wrong hook, the wrong loop and a glue that fails in a dryer.
TrimGem samples sew-on and adhesive tapes as closures next to snaps and buttons. The structure decides whether a cuff still closes after fifty washes, and whether a baby’s wrist is scratched.
The two faces
On a typical nylon woven hook, hook density can sit above 300 per cm², with hook height in a 1.5–2.5 mm band. Loop loft and density are equally specified. Too few hooks: no closure. Too aggressive a hook on a weak loop: the loop pills and dies. Too stiff a hook on skin: a complaint, or a kidswear rejection.
Opening is not a defect. It is the product. The design job is a closure force the wearer can beat, and a shear force the garment cannot.
How the hook is made
Woven hook. The traditional article: extra yarns woven, cut, heat-set into hooks. Harder hand. High cycle life when the nylon is honest. Outdoor, uniform and repeated-open programs live here.
Moulded / injection hook. Molten nylon shot into a tool. Hooks are more regular, often finer and softer. “Doesn’t snag knitwear” is the sales line; the real claim is a rounded hook that is less likely to grab a sweater or a baby’s skin. Cuffs on shells, infant coveralls and many medical wraps use moulded hook.
Mushroom hook. A headed hook (historically associated with 3M’s Dual Lock-type families). Much higher engagement than a J-hook. Overkill on a windbreaker cuff; correct when you need a mechanical lock, not a textile caress.
Loop can be woven, knitted or nonwoven. Apparel volume is woven or knitted nylon/polyester loop. Nonwoven loop appears on disposables.
Backings: sew or stick
Sew-on (no adhesive) is the garment default. You choose the fibre of the tape and you sew it. Nylon, polyester and blends are all available.
Adhesive-backed is the volume industrial SKU: peel the liner, stick. The adhesive is a second product:
- Hot-melt: cheap, indoor, light duty.
- Acrylic: broader temperature, stronger.
- High-temperature acrylics (automotive interiors).
- Silicone: skin-contact medical, gentler, not a car-dash glue.
Adhesive hook-and-loop on a garment that will be washed is a gamble unless the mill has proven the glue through the wash. Sew.
Fibre
- All-nylon: strongest, most abrasion-resistant, firmer hand. Repeated open/close, outdoor, uniform.
- Polyester: cheaper, softer, the disposable and fashion volume play.
- Blends: the apparel compromise.
- Moulded nylon hook: the next-to-skin hook.
Specials: FR, anti-static (cleanroom), wide temperature, OEKO-TEX STANDARD 100 Class I for infant. Those are finishes and certificates, not a different physics.
Where it is used
Apparel cuffs, plackets, pocket flaps, shoe straps, bags. Medical cuffs and braces (biocompatible, often moulded hook). Automotive carpets and harness wraps (temperature, sometimes FR). Infant diapers and coveralls (moulded hook, not a sharp woven hook). Cable ties and electronics. None of those programs share one SKU.
Spec line
Write hook type (woven / moulded / mushroom), loop type, fibre, width, sew-on vs adhesive (and which adhesive), colour, and the peel/shear method from the next note. If you need the Velcro brand, write the brand and the style code. If you need a touch fastener, write hook-and-loop and the construction. They are not synonyms.