A coloured cord of 3 mm may seem unremarkable — light, flexible, easy to handle. But what happens when it is actually loaded to break point?
The combination of material, construction and diameter makes this an interesting test.
The average breaking strength of this 3 mm coloured cord is 0.68 kN (70 kg), based on 5 tensile tests. That is notably low compared to other 3 mm ropes in our test series.
What type of rope is this?
This is a braided cord of 3.0 mm without core, made from polypropylene multifilament (PPMF). The braided construction without core — also referred to as solid braid or hollow braid — gives the cord a flexible structure and a uniform appearance.
Because no core is present, the entire sheath carries the load.
Polypropylene is the lightest of the common synthetic fibres and floats on water. The material absorbs no moisture, which makes it practical for applications where the cord becomes wet.
The colour range makes this type of cord popular for decorative and creative applications: hobby projects, marking, packaging, light fastening, and craft applications such as macramé or decorative knots.
Polypropylene has the lowest UV resistance of the common synthetic fibres. With prolonged outdoor exposure, the material degrades noticeably, reducing breaking strength further.
This cord is therefore not intended for permanent outdoor applications.
Test methodology
The tensile tests were carried out on a universal testing machine with rope-specific clamps, suitable for measuring rope without the use of splices.
All five tensile tests were carried out without pre-tension. The test speed was 20 mm/s.
The cord was loaded to break, with the maximum force at the break point recorded.
5 repetitions were carried out to obtain a reliable average.
Results
The five tensile tests produced the following results:
- Average breaking strength: 0.68 kN (70 kg)
- Highest measured value: 0.69 kN
- Lowest measured value: 0.68 kN
- Number of tests: 5
The spread in results was remarkably small: 3 of the 5 tensile tests gave exactly 0.68 kN, the remaining 2 gave 0.69 kN. A difference of only 0.01 kN across all measurements is exceptionally consistent for a thin braided cord.
This indicates a highly homogeneous construction and a stable production process.
The break in each case was abrupt — one sharp snap per tensile test, notably loud for such a thin cord.
Comparison with other 3 mm ropes
To put the breaking strength of this cord in perspective, a comparison is made with other 3 mm ropes previously tested:
- Kevlar 8-strand braided without core: 5.85 kN
- nylon braided without core: 2.90 kN
- Kevlar sheath with core with 2 twisted cores lying parallel: 2.16 kN
- This PPMF cord (braided without core): 0.68 kN
The difference is significant. The 3 mm nylon cord achieves 2.90 kN — more than 4× the breaking strength of this PPMF cord.
The Kevlar cord with sheath performs at 5.85 kN, more than 8× higher. The coloured PPMF cord is therefore structurally the weakest of the 3 mm ropes tested.
That is not a defect or anomaly — it is a direct consequence of the material (polypropylene has the lowest tensile strength of the common synthetic fibres) and the absence of a core.
When is this cord most suitable?
This cord is most suitable for applications where breaking strength is not a criterion, but ease of handling, colour and cost efficiency are. Examples include:
- Hobby projects: flexible, easy to knot, available in multiple colours
- Packaging and bundling: keeping light items together where a breaking strength of 0.68 kN (70 kg) is more than sufficient
- Marking and demarcation: visible colour, light weight, easy to process
- Decorative knots and presentation: uniformity and aesthetics are primary, mechanical load is negligible
- Temporary indoor fastening: for single-use or short-term applications without structural load
The cord is best suited to situations where it is not subjected to heavy loading and where appearance, flexibility or colour coding is the determining factor.
Limitations
This cord is not suitable for the following applications:
- Permanent outdoor applications: polypropylene degrades significantly under UV radiation. Prolonged exposure to sunlight reduces breaking strength further.
- Mechanically loaded connections: with a breaking strength of 0.68 kN, there is no margin for shock loading, wear or knot losses. Knots reduce breaking strength by 40–60%, which for this cord equates to an effective breaking strength of approximately 27–41 kg with an overhand knot.
- Applications requiring UV resistance: for outdoor use lasting more than a few weeks, polyester or nylon is a better choice.
- High temperatures: polypropylene has a low melting point (approximately 160–165 °C). Frictional heat or high ambient temperature can drastically reduce breaking strength.
Alternatives
If the application requires more tensile load than 0.68 kN (70 kg), there are better options in the same diameter category:
- 3 mm HMPE with black polyester sheath per metre — HMPE (Dyneema) offers the highest strength-to-weight ratio of all synthetic fibres, with a breaking strength many times higher than this PPMF cord. The polyester sheath protects the core and provides good UV resistance.
- Nylon braided (polyamide) (3 mm, Spool 100 metres, White) — nylon achieves 2.90 kN (approximately 296 kg) at 3 mm, more than 4× the breaking strength of this PPMF cord. Nylon absorbs shock loading through its high elongation (20–35% at break), making it suitable for dynamic applications.
Conclusion
This 3 mm coloured PPMF cord has an average breaking strength of 0.68 kN (70 kg) — the lowest of all 3 mm ropes tested.
The notably small spread across the five tensile tests (0.68–0.69 kN) confirms a consistent construction, but does not change the fundamental finding: this is a light cord for light tasks.
This test was carried out by Otto Tromm, who after the fifth identical snap concluded that this cord is consistent — consistently light in load capacity.
The test data were collected by Prorope. This text was generated with AI on the basis of those data and has been verified for factual accuracy. Read how we test and publish →