Hook and Loop Tape: Types, Sizes, Strength and How to Specify It

Hook and loop tape is one of the few closures that can be opened and re-closed thousands of times with no moving parts, no hooks to bend and no tools to install. That simplicity hides a surprising number of variables. Two tapes that look identical on the roll can differ by a factor of five in how much load they hold — and the difference only shows up once the product is in the field.

This guide covers what hook and loop actually is, the materials and formats available, how its strength is measured (and why the number alone is meaningless without its test method), and what belongs on a purchase specification.

Three tiers of confidence are used throughout this guide, and they are not interchangeable:

• Standard — defined by a published test method or unit system (for example ASTM D5169, or ligne = 0.635 mm). Quotable and checkable.
• Convention — widely used trade practice with no governing standard. Treat it as a starting point, confirm it in writing.
• Verify required — typical values reported across the industry. These depend on hook geometry, pile density, engagement pressure and conditioning.

Hook and loop tape — also called a touch fastener or contact fastener — is a two-part mechanical closure:

• The hook component (hook tape) carries a field of stiff, precisely formed filaments. These are usually monofilament extrusions that are heat-set into a hook shape.
• The loop component (loop tape) carries a dense pile of soft loops. The hooks catch in these loops when the two faces are pressed together.

Unlike an adhesive, nothing transfers and nothing cures. The closure works purely mechanically, and it can be separated again by peeling the two faces apart.

The best-known name for this product is a registered trademark, not a generic term. The generic product category is hook and loop fastener or touch fastener. This matters commercially as well as legally — if you write a brand name into a tech pack without qualifying it, you may be specifying a single supplier by accident. Many mills now write “hook and loop tape (brand-type)” for exactly this reason. Use the generic term in specifications unless you specifically intend to buy from that one brand.

The idea is usually credited to the Swiss engineer George de Mestral, who noticed in 1941 that cocklebur (burdock) seed heads clung stubbornly to his dog’s fur and his trousers after a walk in the Jura mountains. Under a microscope he saw that each bur carried hundreds of tiny hooks that engaged any loop passing over them. He spent years working out how to reproduce it in textile form, taking out a Swiss patent in 1951 and a US patent in 1955.

The closure reached public awareness through aerospace — it was used on Apollo spacesuits to attach equipment pouches and helmets — and only later became a garment and consumer standard.

Both components are almost always polyamide (nylon 6 or nylon 6,6) or polyester (PET). Neither is universally better — they behave differently under UV, moisture and repeated cycling. Nylon has a melting point around 220–265 °C depending on the grade (nylon 6 lower, nylon 6,6 higher) and polyester around 250–260 °C; those are material properties, not supplier claims. The practical differences below are directional trends rather than fixed numbers.

Rule of thumb: choose nylon where the closure sees wear but no sun (apparel, footwear, medical); choose polyester where it sees sun, weather or repeated wetting (marine, outdoor gear, automotive exterior trim, anything laundered and line-dried).

Widely stocked widths include 10, 16, 20, 25, 30, 38, 50, 75, 100 and 150 mm, with 20 mm, 25 mm, 38 mm and 50 mm the most common (Convention — ranges vary by mill, and some widths are made to order only).

Because engagement is mechanical, holding force scales roughly with engaged area. If you double the width you roughly double the shear capacity; if you double the engaged length you do the same. This is why the same tape specified by width alone can be “strong” in one application and useless in another — width without an engaged length is not a specification.

Check with your mill about tolerance. A commonly applied trade tolerance on cut width is around ±1 mm (Convention). Confirm it in writing, because a hook tape cut off-centre loses a row of hooks on one edge.

Adhesive backing is where most field failures start. A peel adhesive that holds fine at ambient temperature can creep under sustained load or soften in a hot car. Never specify adhesive hook and loop for a load-bearing closure without a temperature rating.

This is the part that separates a real specification from a marketing number.

There are two fundamentally different ways a hook and loop closure fails, and each has its own ASTM test method:

Key insight: the two numbers are not interchangeable, and the shear figure is always higher. A closure specified only on shear can still peel itself open from a lifted corner — and that is how most of them actually fail in service. Always specify both.

ASTM D5170 offers two ways to calculate the result, and the two are not equivalent:

1. Integrator average — the mean force across the whole trace. Generally lower, easy to compute, well suited to QC.
2. Average of the five highest peaks — the mean of the five largest peaks. Better reflects real opening feel, and generally runs higher.

A peel value quoted without naming which method produced it cannot be compared with anything. This is a common source of false disputes: a supplier’s five-peak result meeting a buyer’s integrator-average limit looks like a defect and is not one.

Verify required — these are indicative ranges compiled from published data, not limits. Always require a test report against your own specification.

1. Pick the material by environment — nylon for wear, polyester for sun and wet.
2. Size by engaged area, not width alone — state width and the engaged length the closure will actually have.
3. Specify both shear and peel — quoting one is the single most common specification error.
4. Name the peel calculation method — integrator average or five-highest-peaks.
5. Specify cycle life and retention — e.g. “≥80 % of initial shear after 10,000 open/close cycles.”
6. Fix the backing and its limits — sew-on vs adhesive; if adhesive, give the temperature range.
7. Give a colour reference — Pantone TCX rather than a name, and expect a lab dip.
8. Require a written width tolerance.
9. Ask for a test report per batch, not per supplier.
10. Approve and sign a physical reference and hold it against future deliveries.

Close hook and loop before washing. Open closures shed lint into their own loop pile and pick up lint from everything else in the machine, and a matted loop field quietly loses most of its holding power. A soft brush restores partly matted loop pile; hooks that have been permanently straightened cannot be recovered.

The best-known brand name in this category is a registered trademark, not a generic term. “Hook and loop”, “touch fastener” and “contact fastener” describe the generic product. Use the generic term in specifications unless you specifically intend to buy from that brand.

It depends almost entirely on the engaged area and on whether the load is applied in shear or in peel. Multiply the area by the relevant strength figure rather than asking for a single number — and note that the same closure will hold far less if the load peels one corner up instead of sliding the faces.

Nylon generally gives higher initial peel and shear values. Polyester holds up better under UV, humidity and repeated wetting. “Stronger” depends on whether you mean on day one or after two years outdoors.

Yes, and it is one of its advantages over most other closures. Close it before washing, keep it away from high heat, and avoid fabric softener residue, which can coat the loop pile.

That the closure was repeatedly engaged and separated 10,000 times and then re-tested. Specifications normally add a retention requirement — without it the cycle figure means nothing, because a closure that survives 10,000 cycles but retains 20 % of its strength has effectively failed.

Sew-on hook and loop tape is designed for exactly that. Use a needle that matches the fabric-plus-tape thickness and avoid running the stitch line through the hook field itself, which both flattens hooks and dulls needles quickly.

Figures in this guide are industry reference values compiled from published test methods and supplier data. Always verify against a test report for the specific product and lot you intend to buy.

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