Reverse-sourcing is the boring half of B2B cordage buying, and the half that decides whether the buyer’s program will run cleanly or whether every shipment is a re-quote. The exercise is simple in principle: take an existing product the buyer wants to replace or supply alongside, capture what makes it that product, and write the description down in an order the supplier can quote against. In practice it fails most often on yarn form — a field that does not show up in a photo and that is easy to skip on a verbal description.
This guide walks through the fields in the order they should be captured, and then through what a photo can and cannot tell the buyer versus what only a physical sample can.
The fields, in the order they should be captured
1. Material
PP, PE, polyester, nylon, cotton, jute, sisal, hemp — or a blend. The material decides the price band and the application envelope (UV behaviour, water behaviour, stretch, hand feel, food contact).
How to capture it: most samples are labelled or accompanied by paperwork. If not, the burn test (small offcut, in a well-ventilated area, observing the smoke, melt behaviour and smell) is the traditional field check, but a confident yarn-form identification is more useful and safer than a burn test alone.
2. Yarn form
This is the field most often missed in reverse-sourcing. Two ropes of the same material and nominal diameter can have very different yarn forms — and yarn form changes price, hand feel and end use.
- Split-film. Flat polymer film, slit and twisted. Most economical; a slight haze and visible fibrillation on the surface.
- Monofilament. Single continuous filament. Smoother surface, slightly stiffer hand feel, used in netting and trimmer line.
- Multifilament. Many fine filaments bundled into a yarn. Soft hand feel, used in braided cords and finer twines.
- Staple / spun. Short fibres spun into a yarn, then twisted. Used in cotton and some natural-fibre twines.
The yarn form is reliably identified from a 10–20 cm cut of the sample, ideally with the cross-section visible at one end. A photo at normal product distance usually cannot distinguish split-film from monofilament.
3. Construction
3-strand twisted, diamond braid, hollow braid, solid braid, double braid, 8-strand plaited, single-ply twine, multi-ply twine. Construction is partly visible from a product photo — twisted vs braided is usually obvious at a glance. The number of strands and the braid density is harder to see and is often a separate field on the supplier’s quotation.
For electric-fence line, the equivalent of “construction” is format: polywire, polyrope or polytape. The detail is in electric fence conductors and resistance.
4. Nominal diameter
Measure the sample with a calliper at three points along its length, and the range. Tolerance matters: a sample at “10 mm nominal” might be 9.6 mm to 10.4 mm depending on the supplier. The supplier’s quotation can be matched against the sample only when the buyer’s measurement is consistent.
For twine, the equivalent of “diameter” is runlength in metres per kilogram, not millimetres. See how rope is measured.
5. Length, weight and runlength
How the line is sold: 200 m coil, 500 m reel, 5 kg spool, 9 kg ball, 30 m cut length. For an existing sample, the buyer’s incoming unit may already have a length or weight on the label; if not, weigh and measure it. The supplier’s quotation needs to know the unit so the per-metre or per-kilogram price can be compared.
For baler twine specifically, the runlength (m/kg) is the field the baler manual and the crop are matched against. See baler twine sizes and runlength.
6. Colour and tracer
Solid colour, two-tone, multi-colour pattern (common in retail diamond braid). Tracers (a contrasting yarn woven into the braid or twist) are common in industrial rope and matter when the buyer is matching an existing line. A short note (“blue with white tracer, 1 tracer per 6 strands”) is more useful than a verbal “blue with tracer”.
7. Packaging format
The reel, spool, coil, ball, hank or cut length the line is sold on — and any printed component on that packaging (label, header card, sleeve, barcode). This is the private-label side of the same sample. If the buyer is replacing an existing retail SKU, the existing SKU’s format is the reference for the new SKU. See private-label cordage.
What a photo can and cannot tell the buyer
A photo is useful for:
- Confirming overall format — twine, rope, tape, braided rope.
- Confirming colour, colour combination and tracer position.
- Confirming packaging format — coil, reel, spool, ball, retail pack.
- Confirming approximate diameter against a reference object in the frame (a coin, a ruler, the buyer’s hand).
- Confirming twist direction (Z vs S) when the photo is at the right distance and the light is right.
A photo is unreliable for:
- split-film vs monofilament vs multifilament yarn identification;
- braid density and strand count;
- precise diameter without a reference object;
- hand feel, stiffness and twist pitch;
- reel length (which the supplier reports separately).
For the first pass at a sample, the photo is a useful sanity check. For the supplier’s quotation, the photo alone is rarely enough — the supplier needs the fields above written down.
What only a physical sample reveals
A short cut of the sample — 10–20 cm is enough for most purposes — exposes what a photo cannot:
- Yarn form. Split-film, monofilament, multifilament, staple — visible in the cut and at the cross-section.
- Construction density. Twist pitch on twisted rope, braid density on braided rope. A loose braid and a tight braid of the same construction look almost identical from a distance.
- Twist direction. Z-twist vs S-twist. Important if the buyer’s downstream use involves splicing against a known construction.
- Diameter against a calliper. A measured figure rather than an estimate.
- Hand feel and stiffness. Determines the application’s working feel; not visible from a photo.
- Smell. Some finishes have a distinctive odour; matters for food-contact and indoor use.
- Conductor count and layout on an electric-fence line. A cut section exposes the conductor material (test against a magnet — stainless steel and tinned copper are non-magnetic; aluminised variants may show weak attraction) and how evenly the conductors are distributed around the jacket.
A physical sample is poor for confirming reel length, winding condition and production batch consistency. The supplier’s reel data and the buyer’s incoming inspection cover those.
A practical capture template
For the first sample the buyer wants to match, the capture can be a single short note:
Material: PP Yarn form: split-film Construction: 3-strand twisted, Z-twist Diameter: 10 mm (9.7–10.2 mm measured across 3 points) Colour: solid blue (Pantone reference on file) Length per unit: 220 m coil, shrink-wrapped Packaging: plain coil, no label; intended for shrink-wrap with branded sleeve Photo attached: shows colour and coil format Cut sample enclosed: ~25 cm for construction, yarn form and conductor check (electric-fence line)
The note is then attached to the photo and the cut sample in the same email or the same package. The supplier can quote against the actual product from one round of correspondence.
When the matching fails
Two reasons the matching fails in practice:
- The buyer sends a photo and a verbal description, but not the cut sample. The supplier quotes against the description; the line arrives close but not exact, and a round of corrections follows.
- The buyer sends the cut sample but does not write down the fields. The supplier has to ask the same questions a second time.
Both are avoidable. The first by sending the sample; the second by writing the fields down on the same page. The two together shorten the round-trip by a week on most programs.
Where to send the sample and the note
The RFQ form walks through the same fields for the buyer’s program and pre-fills a sample-attachment line. For electric-fence line specifically, the electric-fence sample approval checklist covers the additional fields (resistance, conductor count, reel length, UV package) that a fence line needs beyond the standard reverse-sourcing note.