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Carpet Specifications, Testing and Acceptance Checklist
A carpet order often travels as a colour name, a size and a unit price, and those three items are enough to manufacture something visibly similar yet quite different in service. Behaviour is fixed in a handful of measurable parameters: pile height, yarn count, pile density, fibre content, backing construction and the tolerances applied to each.
Pile height is the length of yarn standing above the backing, and it is the fastest way to describe a surface, but it is a weak specification alone. Two carpets can share a nominal 10 mm pile and behave very differently if one uses a fine yarn count and the other a coarse one. Height describes the look; count and density describe wear.
Total pile weight in grams per square metre is the most portable comparison figure because it combines height and mass in one number. Density must always be quoted with its measurement basis, since tuft density per square inch and pile density per square metre are calculated differently. The order should state pile height in millimetres with a tolerance, nominal yarn count, total pile weight, tuft density with its basis, and the finished size with its permitted deviation.
| Parameter | How it is expressed | What it controls | Wording on the order |
|---|---|---|---|
| Pile height | Millimetres above the backing | Softness, direction, cleaning effort | Nominal figure plus tolerance |
| Yarn count | Metric or denier yarn diameter | Fineness of the surface | One named count, not a range |
| Total pile weight | Grams per square metre | Material content and durability | Minimum acceptable value |
| Tuft density | Tufts per unit area | Resistance to crushing and shedding | Figure with measurement basis |
| Finished size | Length and width | Yield and cutting plan | Dimensional deviation allowance |
Height also sets practical limits: below roughly 6 mm the surface is firm and easy to vacuum, which suits hallways and offices, while above 9 mm it becomes deep and strongly directional, suited to rooms where appearance rather than wear resistance decides the outcome.
Abrasion resistance is the property buyers most often request and most often receive in an unusable form. The Martindale approach rotates a specimen against an abrasive disc under load and counts the cycles to a defined endpoint. The other expresses wear as a class, from light domestic to heavy contract use, derived from fibre, density and construction.
A figure quoted without the test method, specimen conditioning and endpoint carries little weight. Name the method, the minimum accepted value and the class required for the space, and record the same requirement for every colourway, since one colour may reach the class on a heavier construction than another.
| Test or property | What it measures | Basis | Statement required |
|---|---|---|---|
| Martindale abrasion | Cycles to a defined endpoint | Rotary abrader under load | Method plus minimum cycles |
| Wear class | Intended traffic level | Fibre, density and construction | Class for the room |
| Pile density | Tufts per unit area | Count over a measured area | Value with measurement basis |
| Colour fastness | Light, wash and rubbing | Named test and grey scale | Tests with minimum rating |
| Dimensional change | Movement after wetting or heating | Conditioned specimen | Maximum percentage deviation |
Density is the quieter half of the durability equation. A hard-wearing fibre set in a low density carpet will crush and shed long before the fibre wears out. A useful check is to press the pile and release it: a dense surface recovers quickly and leaves a clean mark, while a loose one stays flattened.
Colour performance is tested along several dimensions, and naming the dimension matters as much as stating the value. Light fastness measures resistance to fading, wash fastness measures colour loss when a specimen is washed, and rubbing fastness measures transfer to an adjacent white textile under dry or wet conditions. A contract that says only colourfast is read differently by every factory, so the tests must be named.
Shade variation is a manufacturing reality rather than a defect, but it has to be controlled by agreement. Continuous dyeing of a finished roll gives good matching within the piece and between pieces cut from the same dye lot. Solution-dyed yarn carries pigment through the whole fibre, which removes dye-lot variation entirely. Batch dyeing leaves shade differences between lots that become obvious along a seam. State the number of dye lots permitted per order and guarantee that different lots are not mixed in one room.
Patterned goods add a second issue, which is repeat alignment. A pattern with a defined repeat length must be allowed for in cutting, and the repeat should be recorded so a replacement piece can be matched later. Cutting tolerance on pattern goods is tighter than on plain goods. Where a pattern crosses a seam or changes direction between rolls, the lay plan should state which roll leads and how the pattern is turned.
The backing is the structural half of a carpet and the half most often checked last. Tufted goods use a woven primary backing into which yarn is tufted, a binder coating, and usually a secondary backing that gives the roll its stiffness and stability. At inspection, flex the backing: it should not delaminate, crack at the fold line, or leave a powdery binder on the fingers.
Underlay is not part of the carpet and is frequently excluded from the order, which is a mistake whenever anti-slip performance is required. Foam suits loop pile in low-traffic rooms, felt or rubber suits cut pile where grip is wanted, and a heavier sheet grade is needed where castor chairs run. Where slip resistance is specified, the carpet and underlay pairing should be approved together.
Cleaning guidance belongs in the specification because it determines whether the stated performance will be realised. Wool and wool blends need mild, pH-controlled products, while polypropylene is chemically stable. Solution-dyed nylon resists staining at fibre level, so spills are easier to remove because the stain sits on the surface rather than inside the yarn.
Care instructions should cover the maintenance schedule rather than only the emergency response: vacuum frequency, the recommended vacuum type, the spot treatment procedure, and the point at which professional extraction becomes necessary.
Most complaints arrive as a symptom rather than a cause: shading in a traffic lane, a bald area near the door, a colour difference across a seam, a lifting edge, a smell after cleaning.
Because many of these faults are visible or measurable on delivery, the sequence below doubles as an inspection sheet. Run it on an opened sample area before the goods are laid, and record results against the order rather than against a photograph.
| Symptom | Likely cause | Check at receipt |
|---|---|---|
| Traffic lane shading | Directional pile or low density | Review density figure and wear class |
| Bald patch | Crushed tufts from low density | Press and release the pile |
| Seam colour difference | Mixed dye lots | Check lot labels against the order |
| Edge lifting | Weak anchoring or wrong underlay | Inspect edge and subfloor fixings |
| Fading or transfer | Weak rubbing fastness or strong cleaner | Review fastness results and cleaning guidance |
| Odour after cleaning | Residue from an unsuitable product | Review the stated cleaning regime |
A fault visible across a whole roll is usually a manufacturing or dye-lot issue and should be raised before installation, because a laid floor is harder to argue about. Shading and traffic-lane changes are inherent to any cut pile carpet and are not defects unless they exceed an agreed limit, so they belong under wear rating and pile specification rather than under a claim.
A workable order names the fibre and blend percentages, the construction, pile height with tolerance, yarn count, total pile weight, tuft density with its basis, the abrasion method and minimum value, the wear class, each colour fastness test with its minimum rating, dimensional tolerance, backing structure, underlay requirement and edge finishing.
Specify a medium pile of roughly 6 to 9 mm with total pile weight and tuft density stated alongside it, since height alone cannot predict how the surface wears. A high abrasion figure paired with a low density figure is a weak combination, because the tufts crush before the fibre does. Confirm that the same parameters apply to every size in the range, including remnants.
Neither replaces the other. The Martindale figure measures cycles to a defined endpoint under a stated machine and load, which makes it useful for comparing products tested the same way, while the wear class summarises the traffic level a product is designed for. A figure quoted without the method and endpoint cannot be compared with anything. Name the method, the minimum value and the class required.
Fewer is better, and the number should be agreed before cutting. Continuous dyed goods matched from one dye lot give consistent shading across a room, while batch dyed goods carry visible shade differences between lots that show along a seam. Specify the maximum number of lots permitted in one order and the rule that lots are not mixed within a room. In a long corridor run, solution-dyed yarn removes the issue because the pigment is in the fibre.
Only where performance, appearance and slip resistance are not part of the acceptance criteria. Underlay governs how much pile height is usable, how rolling loads are handled, how the edge stays anchored and whether the carpet grips the subfloor, so a carpet assessed apart from its underlay cannot be judged fairly. Specify the underlay grade, thickness and coverage, and approve the carpet and underlay pairing as one system before ordering.
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