Two tapes can look identical on a sample card and behave nothing alike in production. The difference is not the colour or the width — it is how many hooks engage, how deep they go, and what happens to them after the five-hundredth opening.
What is actually happening when you press the two halves together
Hook tape carries small monofilament hooks woven into a ground cloth. Loop tape carries a brushed pile of finer yarns. Press them together and the hooks penetrate the pile and catch. Nothing is sticky. The joint holds because hundreds of tiny mechanical anchors are resisting being pulled apart at once.
Three variables decide how strong that joint is:
- Hook density. Hooks per square centimetre. A cheap tape might carry 60; a heavy-duty woven face carries 120 or more. Doubling density does more for peel strength than doubling adhesive ever will.
- Loop pile height and fineness. A taller, finer pile lets more hooks bury deeper. A short, dense pile feels nice but releases too easily under shear.
- Engagement depth. How far the hooks sink in before you stop pressing. This is why the same tape holds 1 kg when pressed by hand and 2.5 kg after being run through a nip roller.
Why the tape in your sample bag failed on the line
Almost every complaint we receive reduces to one of four causes. None of them are the adhesive.
| Failure | What you see | Real cause |
|---|---|---|
| Hooks flattened | Holds at first, loosens after repeated opening | Hook monofilament too soft or too thin for the load; deformed permanently under compression. |
| Loop fuzzing | Loose fibres on the loop face, strength drops steadily | Low-tenacity loop yarn; the pile is being torn out rather than released. |
| Peel at the edge | Lifts from a corner first, then unzips | Edge is not sealed after slitting. Frayed edges start the peel. |
| Shear slip | Holds when peeled, slides when loaded sideways | Engagement is shallow — usually the wrong loop for that hook, or too little closing pressure. |
Cycle life is a design decision, not a specification
Every opening and closing bends the hooks a little further. A general-purpose nylon tape survives around 5,000 cycles before peel drops below 80% of its initial value; a heavy-duty face gets to 10,000; an injection-molded hook can exceed 20,000 because the hook is a moulded shape rather than a woven one.
If your product opens once a week for five years, that is 260 cycles — almost anything works. If it is a cable tie that a technician reopens daily for a decade, that is 2,600 cycles and the cheap tape will look tired by year three.
What we measure, and what we will not claim
Peel strength is measured on a tensile tester to ASTM D5170, shear to D5169, on 25 mm wide samples, after a 24-hour dwell at 23 °C. Numbers in our catalogue are lot averages, not best-case lab results. If a batch falls outside the agreed window, it does not ship.
The number we will not give you is a single “holding weight”. Hook and loop holding capacity depends on load direction, engagement pressure, temperature and cycle count. Anyone quoting one figure for all four is selling you a number, not a fastener.
Rule of thumb for specifying
Start with the load direction. Peel (opening like a book) needs high hook density. Shear (sliding along the surface) needs deep engagement and a tight loop. If the load reverses direction, specify back-to-back tape so both faces grip, and add a mechanical stop so the fastener never carries the full load alone.
Need this applied to your part?
Send the substrate, the load and the drawing. We will come back with a construction, a tolerance and a sample date.
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