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Climbing rope manufacturing

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Climbing rope manufacturing

Climbing Rope Manufacturing

Image from: mammut.com

Written in November 2023.

The relevance of information might change over time.

Written in November 2023.

The relevance of information might change over time.

“A Climber and a Rope” – sounds like a perfect story of friendship.

But what kind of friendship would it be if the climber and the rope are barely interested in getting to know each other...? Well, it might be hard to blame the rope for the lack of curiosity, but having an indifferent climber, whose life depends so much on his textile companion, is a shame!

So let’s not put the strength of such a valuable friendship to the test, but rather begin to strengthen it. And it seems logical to start from the very beginning – with a tale of how, from the smallest fibers, a strong and beautiful rope is born. A rope that will accompany you on all your journeys, no matter how hard they are and how far they will get you both.

You, your rope, and faraway lands.

Image from: climbing.com

For the purpose of this article, climbing ropes refer to both static (EN 1891) and dynamic (EN 892) ropes with kernmantel construction.

Contents:

KERNMANTEL CONSTRUCTION
WHAT MATERIALS ARE CLIMBING ROPES MADE FROM?
RAW MATERIAL SOURCING
TWISTING
CORE STRANDS PREPARATION
SHEATH YARNS PREPARATION
BRAIDING
SHEATH IMPRENATION
QUALITY CONTROL
CUTTING
MIDDLE MARKING
LABELING
COILING & PACKAGING
RESOURCES & BONUS MATERIALS

Kernmantel construction

All modern climbing ropes, whether static or dynamic, utilize the Kernmantel construction (from German “kern” – core, and “mantel” – shell, sheath). This construction, as the name suggests, involves an inner core that bears the main load and an outer sheath that protects it from external influences. Developed in 1953 by a German company Edelrid, this construction radically increased the safety of mountaineering and its related disciplines. But the real revolution unfolded later, in 1964, when the same company introduced the first dynamic ropes, made possible not least of all by incorporating the kernmantel design.

A kernmantel rope consists of a load-bearing core and a protective sheath.

Image from: wikipedia.org

You’ve likely seen the distinctive parts of the kernmantel construction we are talking about – the colorful sheath “stocking”, braided as a dense layer of yarn around the white core, constructed with thick, twisted, parallel-located strands. You definitely don’t need to be an engineer or rope production technologist to understand that these two are manufactured differently. But we'll delve into that in due course. For now, let's begin with an exploration of the materials used for making both the core and the sheath.

Not the best view to discover on the route.

Image from: climbinghouse.com

What materials are climbing ropes made from?

All modern climbing ropes are made exclusively from synthetic materials, with polyamide (PA) being the primary one.

Polyamides represent a vast group of plastic polymers, among which Nylon® stands out first. Synthesized and patented by the DuPont company in 1935, Nylon has subsequently undergone various modifications. Nowadays, Nylon 6.6 and Nylon 6 are the most commonly used in the textile industry in general and rope manufacturing in particular. Those two are the materials of choice for all dynamic and most static ropes due to their optimal balance of price and properties, including high elasticity and tensile strength.

However, not all polyamides are the same. Consider the group of aromatic polyamides, also known as aramids, with Kevlar® being the most famous representative. Ropes incorporating aramid are typically expensive, specialized models designed for increased heat and wear resistance, as well as very low elasticity (in contrast to classic Nylons).

“Swift Protect” 8.9 mm dynamic rope from Edelrid. A model that successfully passes all dynamic tests according to the EN 892 standard, despite the fact that its sheath partially consists of superstatic aramid fibers. This feature not only represents a technological breakthrough but also serves to significantly increase the rope's cut resistance.

Image from: edelrid.com

The second most popular material is polyester (PES). It is used significantly less than PA and mainly for the manufacturing of static ropes in cases where it is necessary to achieve a low elongation coefficient and increased wear resistance at a reasonable price. And these two are basically all the materials…

“But wait!” – someone will say. “I know for sure that there are also ropes made of polypropylene and polyethylene, including ultra-high molecular weight polyethylene (UHMWPE, for example Dyneema®). Why weren’t they mentioned?” The reason is that those ropes cannot be classified as climbing ropes in a formal sense since the EN 1891 standard for low elongation ropes (in other words, “static ropes”) requires synthetic fibers used to have a melting point of at least 195° C. Both polypropylene (PP) and polyethylene (PET) have lower melting points, which creates a risk of rope melting in certain situations. As for the production of dynamic ropes, both these materials lack the required elasticity. Such is the story.

There are hundreds of models of climbing ropes, and only a few materials used to produce them.

Image from: livejournal.com

So, we’ve answered the question “what” materials ropes are made from. Next, we move on to the “how” question, where we will discuss the stages of rope manufacturing. But before we begin, a small disclaimer: some of the production details, technologies, and machines used can vary significantly from manufacturer to manufacturer. Edelrid, Beal, Tendon, Cousin Trestec, Sterling Ropes, Kolomna... Each manufacturer will have its own nuances. What we will try to do is to capture the general picture and the sequence of actions typical for most productions. So, let's begin!

With a bit of manufacturing magic, the raw material is transformed, transformed... into an elegant rope!

Image from: mountainequipment.com

Raw material sourcing

As mentioned earlier, the primary material for the production of most static and all dynamic ropes is polyamide. This plastic is melted, extruded, and drawn into ultra-thin fibers. These fibers are then wound on spools to form the yarn, which serves as the raw material for making ropes.

Rope manufacturers typically do not produce the raw material themselves. Instead, they tend to purchase spools of nylon yarn from third-party companies. And from this exact moment, our tour to the rope production site begins.

For rope manufacturers, it all starts with spools of polyamide yarn.

Image from: barnet.com

According to Edelrid, one nylon sheath fiber consists of up to 135 ultra-fine filaments, while a core fiber has even more – up to 200. Thus, the fibers that arrive at the rope factory can differ in thickness depending on the tasks and the design of the production line. The yarns can also be pre-twisted or, for example, wound in pairs.

A polyamide (nylon) fiber used to make most climbing ropes.

Images from: WeighMyRack, Edelrid Ropebook

Usually, nylon yarns are supplied to rope manufacturers undyed, i.e. white. This is how they will remain if they are meant to form the rope’s core. However, if they are destined to become the rope’s sheath, then either the yarns are purchased already colored, or will be dyed at one of the subsequent stages, which we will discuss separately.

A noteworthy detail is that certain manufacturers, like the already mentioned Edelrid, use bluesign® certified materials and production technologies. The bluesign® mark guarantees that a product is made from environmentally friendly, low-pollutant materials and reflects a high level of human health and environmental protection.

Spools of nylon. The colored yarns, without doubt, will be used to create the sheath.

Image from: marlowropes.com

Twisting

Twisting is a multi-stage process during which a number of fibers are twisted together to produce thicker yarns and strands. Twisting is performed on a variety of twisting machines.

The actual way fibers are twisted depends on whether the resulting yarns or strands will be used for the production of the core or the sheath, in static or dynamic ropes, and the desired characteristics of the future rope.

The twisting parameters that influence the characteristics of the future rope include:

1) Number of fibers twisted together

The more fibers twisted, the thicker the resulting yarn will be. Thicker yarn contributes to a thicker sheath and its larger share in the total mass of the rope (all else being equal). An increase in the proportion of sheath contributes to greater wear resistance but lower tensile strength of the rope.

Edelrid, for example, twists the sheath yarns in groups of 2, 3, 4, or 5, depending on the required characteristics of the final rope.

Twisting of sheath yarns at the Edelrid factory in Germany involves the fibers traveling several meters over a network of rollers that act as guides and control tension on each individual fiber. They pass through distribution plates as turning bobbins below twist the fibers into yarn.

Video from: Edelrid

2) Number of twists per unit length

Which in turn determines:

Tensile strength. The more the yarn is twisted, the less strength it has. The fewer twists and the more aligned the individual fibers are, the higher the tensile strength. Edelrid, for example, twist their sheath yarns 110 to 140 times per meter.

The twisting process is always conducted under a certain level of tension.

Video from: Decathlon

Elongation capacity. This increases in proportion to the number of twists per meter. Thus, in dynamic ropes, unlike static ones, the core strands are much more twisted, allowing them to stretch under heavy loads like a spring.

A rough scheme of static and dynamic Kernmantel ropes

A rough scheme of Kernmantel ropes: on the left – static, on the right – dynamic ones. In dynamic ropes, the core strands are much more twisted, allowing them to stretch under heavy loads like a spring.

Abrasion resistance. The more the yarn is twisted, the more resistant it is to abrasion.

Rope with twisted sheath yarns has increased abrasion resistance.

Images from: Edelrid Ropebook, Edelrid.com

Rope with parallel sheath yarns loses in abrasion resistance, but benefits in tensile strength.

Images from: Edelrid Ropebook, Edelrid.com

That is to say – twisting affects virtually everything. But there’s been too much theory! Let's return to manufacturing, where, as a result of the first twisting stage, polyamide fibers are twisted into basic yarns.

Twisting of the polyamide fibers into basic yarns. A platform moves up and down to evenly wind the yarns into the bobbin.

Video from: Tendon

Subsequently, these basic yarns undergo two parallel production processes:

Preparation of core strands.
Preparation of sheath yarns.

To avoid confusion, let's consider them separately. And we'll start with the core.

Core strands preparation

Core stands of a dynamic climbing rope.

Image from: climbonequipment.com

Twisting of basic yarns into core strands

At this stage, typically 3 to 5 basic yarns are twisted together to form the core strands for the future rope. Here, they take on the familiar appearance we see in every cut rope – white, thick, and twisted.

Basic yarns are twisted into core strands.

Videos from: Tendon, Edelrid

An interesting detail is that the strands (not only the core ones) are twisted differently. Some strands are twisted clockwise – these are the so-called right twists or “Z” twists. Others are twisted counterclockwise, forming left twists or the “S” twists. By alternating different strands, the balance is maintained, necessary to ensure that the user does not rotate while hanging on the rope.

Left (S) and right (Z) twists on the core strands of the rope.

Images from: Sterling Rope tech manual

Unwinding the core strands from spools into loose skeins

Next, the core strands must undergo the thermo-balancing process, also known as shrinkage. To ensure uniform treatment of all strands, they are first unwound from tight spools into loose skeins, which are then laid out or hung on special racks.

The core strands are taken off the spools for further shrinking in the autoclave.

Video from: Tendon

On the left you can see how the core strands are unwound from spools for further conditioning in the autoclave – the big “barrel” on the right. Sterling Rope factory, USA. Image from: ukclimbing.com

Spools and skeins of core strands. Image from: Tendon

Skeins of core strands hung on racks, awaiting their turn to be “cooked” in the autoclave at the Edelrid factory. Image from: Edelrid

Core shrinking

Preparing core strand skeins for shrinking

Preparation of the core strand skeins for shrinking in the Tendon autoclave.

Image from: Tendon

The shrinking of core strands (as well as sheath yarns) takes place in the autoclave, a kind of giant pressure cooker. Here, the strands are intermittently compressed under the influence of temperature, humidity, pressure, and sometimes chemicals. All according to specified programs that vary depending on the manufacturer's goals.

The thermo-balancing stage is very important as it enables manufacturers to tailor the characteristics of the yarn. In brief, shrinking allows the reorientation of molecular bonds, thereby relieving the tension accumulated during twisting, winding, and tensioning processes in the preceding production stages. As a result, the size and properties of the strands stabilize, significantly improving the characteristics of the future rope. Both the core strands and the sheath yarns undergo the same shrinking process (though separately) to ensure consistent condition and behavior during the rope's use.

It's worth noting that not all ropes undergo thermo balancing. Many budget static models (at least here, in Russia) skip this stage, leading to considerable shrinkage during use. Additionally, such models tend to stiffen, making them quite challenging to use.

Removing the shrunken strands from the autoclave at the Edelrid factory.

Video from: WeighMyRack

In the autoclave strands and yarns can shrink up to 30% of their original length. Just look at the rack on the left with the core strands that have already been processed and compare it with the rest. The same effect as washing a wool sweater at high temperature.

Video from: WeighMyRack

Alternative method of core shrinking

French manufacturers Beal and Cousin Trestec approach the shrinking process from a different angle. Instead of placing the core strand skeins in a giant autoclave for a couple of hours, they use a special conveyor to shrink a small amount of core strands but within a couple of minutes. Which of the two production methods is more effective, unfortunately, is unknown…

Core strands shrinking conveyor at Beal factory in France.

Video from: EpicTV Climbing Daily

Core impregnation

At this stage, the shrunken core strands are coated with a water-resistant compound. This step is optional and is undertaken only if the future rope requires full treatment, involving the impregnation of both the core and the sheath.

“Bathing” the core strands in the water-resistant compound at Edelrid.

Video from: WeighMyRack

Additionally, some manufacturers apply dye to the core strands to easily determine whether they have been impregnated or not. This does not affect other characteristics in any way.

The pinkish spools on top contain the dry treated core strands. The white strands at the bottom are non-treated. Image from: WeighMyRack

Pay attention to the color of the core strands of one of the ropes. Red dye indicates the presence of water-resistant coating. You can also determine it by taste. Just don’t get used to it :) Image from: edelrid.com

After the shrinking and optional impregnation processes, the core strands are rewound onto the spools, thereby marking the completion of their preparation stage. Now, attention turns to the sheath.

Sheath yarns preparation

Knitting sheath yarns into bundles

After the twisting stage, the basic yarns intended for the sheath are unwound from spools and knitted into long bundles of yarn (aka “hoses:) using a special machine. This, just like with the core strands, is necessary for the subsequent uniform conditioning of all the material in the autoclave. However, this trick doesn’t work with the core strands because, as you may recall, they undergo an additional twisting stage, resulting in strands that are too thick for such “knitting”.

Unwinding the sheath yarns from spools and knitting them into loose bundles at the Tendon factory. Video from: Tendon

Knitting sheath yarns into loose bundles at the Tendon factory. Video from: Tendon

Knitting the sheath yarns into loose bundles at the Edelrid factory. Video from: Edelrid

Knitting the sheath yarns into loose bundles at the Edelrid factory. Video from: WeighMyRack

Sheath shrinking

To ensure that the sheath strands have the same characteristics as the core strands, they are also placed in an autoclave to shrink.

Bundles of sheath yarn on a rack ready for the autoclave. Image from: Edelrid

Colored sheath bundles after shrinking at the Tendon factory. Image from: Tendon

Sheath dyeing

Some manufacturers, such as Edelrid and Tendon, receive the raw material for the sheath already dyed. Others, like Beal, use this stage to send the sheath yarn to be dyed and shrunk to a partner enterprise.

The French manufacturer Beal utilizes the services of a partner company for sheath shrinking and dyeing. Here's how the shrunken and dyed sheath bundles look like upon their return to the Beal factory.

Image from: EpicTV Climbing Daily

De-knitting the sheath yarns

Next, the bundles are de-knitted and the shrunken sheath yarns are wound onto special bobbins. These bobbins will be mounted on the braiding machine to unite the sheath yarns and core strands in the next step.

De-knitting the sheath bundles. Video from: WeighMyRack

Winding of the shrunken sheath yarns onto bobbins. Video from: WeighMyRack

De-knitting and winding of the shrunken sheath yarns onto bobbins. Video from: Tendon

Braiding

Dynamic rope braiding. Edelrid.

Video from: Edelrid

Braiding is the key stage in rope production, where sheath yarns are braided around parallel core strands, thus bringing together the individual components and giving birth to the rope.

It is important to understand that during the braiding process, the sheath and core do not interconnect unless special technologies are employed, such as Beal's «Unicore», Tendon's «TeFix», Edelrid's "Sync Tec," and others.

Braiding machine working principle

Braiding is carried out on circular braiding machines, or simply braiders. The work of a braiding machine can be compared to a maypole dance, where numerous colored sheath yarns braid around the core in a swift and intricate roundelay.

A circular braiding machine and a maypole.

Images from: marlowropes.com, unitedway.org

A braider with 40 carriers braids the sheath around the core.

Video from: WeighMyRack

In the center of the braiding circle, the core strands are positioned. According to Edelrid, static ropes require 13 to 22 core strands, while dynamic ropes typically need fewer. These strands, under a specific tension and at a certain speed, pass through a distribution plate and converge at the so-called "braiding point," where a "mesh" of protective sheath begins to form around them.

Dynamic rope braiding. Here you can see how twisted strands of the dynamic core pass through the distribution plate of the braiding machine.

Video from: Edelrid

The braiding point in slow motion.

Video from: insidertech

The sheath is formed by a number of colorful bobbins mounted on so-called “carriers”. These carriers travel along tracks that encircle the core. Each carrier is equipped with a tensioner through which the sheath yarns are brought together to the braiding point.

The size of the sheath bobbin carriers, as well as their number in the braiding circle, is what braiding machines primarily differ in.

Installation of a sheath yarn bobbin on a braiding machine carrier

Installing a bobbin with sheath yarn on a braiding machine carrier.

Video from: Tendon

Climbing ropes are braided using two groups of bobbins, thus always resulting in an even number of bobbins. Each group circulates along the track in its own direction: one moves clockwise, and the other counterclockwise. The smallest round braid design can be made from 4 strands, and the largest number of strands used at the moment is 48.

Both bobbin groups circulate on two separate phase-shifted tracks on the braiding machine. One group always moves in a clockwise direction, the other counterclockwise.

Videos from: WeighMyRack, Decathlon

Carrier tracks.

Video from: Edelrid

Another decisive variable is the size of the bobbins. Naturally, larger bobbins can accommodate more material. This can lead either to an increase in the length of the yarn, consequently expanding the production batch, or to the thickness of the yarn, thereby increasing the thickness of the rope sheath. The downside of using braiding machines with larger bobbins is that they tend to operate at a slower pace, resulting in lower productivity and output rates.

Size of bobbins of circular braiding machines

A braiding machine with 40 medium-sized bobbins vs a machine with 16 large-sized bobbins.

Image from: edelrid.com

Braiding factors

At the braiding stage, there are five main factors that influence the characteristics of the resulting rope:

1) Tension of the yarns

Demonstration of the sheath yarn tension on the Edelrid braider.

Video from: WeighMyRack

2) Braiding angle
3) Diameter of the hole the rope is being pulled through.
4) Speed at which the rope is being pulled through the machine, relative to how quickly the bobbins are braiding.

Braiding angle, braiding speed, even the diameter of the hole through which the rope is pulled – all will affect the characteristics of the final rope.

Video from: WeighMyRack

All these factors must be considered and well balanced. Because even a slight increase in the angle and tension of braiding, or a reduction in the hole diameter, can result in a tighter sheath, making the entire rope too stiff and impossible to use.

It is also crucial that each parameter remains constant throughout the entire braiding process. If, for example, the tension of the sheath strands is unstable, the rope may turn out to be too rigid in some areas and soft and spongy in others. Moreover, it can lead to a high degree of sheath slippage relative to the core. Few people will appreciate such surprises.

The last factor will be discussed separately.

5) Number of carriers (bobbins)

The number of carriers on a braiding machine corresponds to the number of yarns (in this case sometimes called “strands”) that form the sheath. The higher the number of yarns, the finer is the sheath pattern, and the smoother its surface. This contributes to less friction and increased abrasion resistance of such ropes, but it also increases the cost of their production. The advantage of ropes made with less carriers is their better grip. These ropes are much easier to work with barehanded.

Most climbing ropes are made on braiders with 16, 24, 32, 36, 40, 48 carriers and have the corresponding number of yarns. For example, dynamic ropes are mostly 40 and 48-”strand” models.

Correlation between the number of sheath strands and the sheath pattern

The more sheath strands, the thinner the sheath pattern.

Image from: marlowropes.com

What’s curious is that the number of carriers on the braiding machine does not always affect such parameters as the diameter of the rope, the thickness of the sheath and the percentage of sheath mass relative to the core. This is because the manufacturer can compensate for the increased number of sheath strands by using thinner or otherwise twisted yarn.

Braiding pattern

In addition to the number of bobbin carriers, the appearance and properties of the rope are also influenced by the braiding pattern of the sheath. The difference between braiding patterns is how the unidirectional sheath yarns pass under and over other yarns.

For circular braiding machines, there are two main braiding patterns:

Plain braid
Twill braid

On the left you can see a plain braid: 1 yarn over 1 yarn and 2 over 2. On the right is a twill braid: 1 over 2.

Image from: edelrid.com

In a plain braid, a given number of yarns always passes over and under the same number of yarns in the opposite direction (for example, 1 over 1, 2 over 2). In contrast, in a twill braid, the yarns are braided with an offset, passing through a larger number of yarns in the opposite direction (for example, 1 over 2).

Try to determine for yourself where the plain braid (2 ropes) is and where the twill braid (3 ropes) is.

Image from: switchbacktravel.com

As always, each option has its advantages. The twill braid pattern is more resistant to abrasion because the smooth surface it creates reduces friction between the rope and other objects. However, the sheath becomes smooth not only on the outside but also on the inside. This means that ropes with twill braids are potentially more prone to sheath slippage during use.

However, not everyone needs a smooth sheath. When working with some devices, and especially with bare hands, a good grip is necessary. This is where the plain braid wins.

Identification tape and tracer thread

A rough scheme of a certified kernmantel rope. Here the identification tape and the colored tracer thread are shown together but, in practice, you are more likely to find only one of these: the identification tape in static ropes and the tracer thread in dynamic ones.

Image from: edelrid.com

During the braiding process, the following must be incorporated into the core of certified ropes:

Identification tape for static ropes (EN 1891)

The identification tape is a thin strip of polypropylene that runs along the entire length of the rope. It recurrently states the basic information about the rope, including the name of the manufacturer, the standard number, the type of rope, the year of manufacture, as well as the name of the material from which it is made.

An example of identification tape hidden in the middle of a static rope core.

Images from: petzl.com, azotfortis.by

Tracer thread for dynamic ropes (EN 892).

The tracer thread is made of polyamide and comes in one of 10 colors specified by the manufacturer. Each color corresponds to the year of production and is repeated every 10 years. This is quite logical, considering that the maximum shelf life of modern ropes is also 10 years.

It is essential to note that each rope manufacturer has its own set of tracer colors. Therefore, to determine the production date of your specific rope, you must first revise the manual or visit the manufacturer's website.

Colored tracer thread inside a dynamic rope

The green color of the tracer thread in this Edelrid's dynamic rope corresponds to the year 2015. Previously, this color was used in 2005 and will reappear in 2025.

Video from: Edelrid

Sheath impregnation

Similar to the core strand impregnation stage, sheath treatment is optional. However, this time, not only the strands but the entire rope is immersed in a bath of water-resistant compound. Despite how it may appear, this process affects only the sheath. After bathing, the rope undergoes heat treatment, where it dries and cools.

Sheath impregnation at Tendon (left) and Edelrid (right).

Videos from: Tendon, WeighMyRack

An alternative way to impart the water-resistant properties to a rope is to soak all the fibers of the material at the raw material stage. This is what the American company Sterling Rope does, calling its new technology Xeros.

The rope manufacturer receives the processed fibers from the supplier, thereby eliminating the need to go through the stages of impregnating the core and sheath in special baths. Sterling claims that this approach is more environmentally friendly, less labor- and energy-intensive, and therefore economical, which also affects the price for the end consumer. Moreover, according to the manufacturer, the impregnation itself does not fade away with use, as happens with “standard” types of water-proof treatment.

Whether this is true, and which approach is better, remains a debatable question :)

Sterling Ropes Xeros impregnation technology

Xeros rope impregnation technology by Sterling Rope.

Image from: sterlingxeros.com

Overall, depending on the nature of the water-resistant treatment, ropes are divided into:

Not treated
Partially impregnated, where only the sheath is coated.
Fully impregnated, where both the core and the sheave have a water-resistant coating. These models are also called “dry ropes”.

The compound itself is unique for each manufacturer. While Teflon™ or its analogues were widely used in the past, the rise of environmental awareness has led to the increased use of various ECO-compounds. For example, my beloved Edelrid, specifically its Swift Eco Dry 8.9 mm, was the first PFC-free and PFAS-free rope to pass certification and receive the “UIAA Water Repellent” mark. Subsequently, most leading manufacturers have set themselves the goal of completely switching to environmentally friendly impregnations during the 20s.

Swift Eco Dry 8.9 dynamic rope from Edelrid is the first model with environmentally friendly PFC-free water coating.

Image from: edelrid.com

Speaking of certification, if a dynamic rope undergoes “full impregnation”, meaning waterproof treatment of both the core and sheath, then it can qualify for the title “UIAA Water Repellent” if it passes the UIAA-101 standard certification. Such ropes absorb less than 5% moisture relative to their own weight. The aforementioned Swift Eco Dry model from Edelrid, for example, absorbs between 1 and 2%. But what does this actually mean to the user?

Dry ropes:

Virtually do not absorb moisture, remaining light and maintaining strength.
Exhibit significantly better abrasion resistance.
Feel smoother, sometimes even slippery. The low friction associated with this effect can be an advantage, reducing wear on the rope and making it easier to pull through some devices. However, it can also be a disadvantage, causing the rope to slip more in hands, devices, and knots. In any case, the “slippery” effect, as well as the water-resistant properties of ropes, tend to decrease with use.

Testing the ropes' water-resistant properties according to the UIAA-101 standard.

Video from: Mammut

But the slippery feeling is not the only tactile property of the rope that impregnation changes. For example, an initially stiff rope might become soft and flexible after the impregnation. Manufacturers take this effect into account, especially when producing dry and non-dry versions of one model. In each case, the yarns undergo their unique cycles of twisting, shrinking, and braiding, ensuring that the ropes have a consistent feel, regardless of the coating.

Quality control

Next, the rope enters the quality control stage, where each meter of rope undergoes visual and tactile inspection to identify and record the slightest defects and deviations. Manufacturers, especially those adhering to ISO 9000 quality standards, are particularly meticulous in this matter. An inspiring fact is that despite the presence of automated sensors, the final control is always performed by a human.

Heterogeneity in the material? A stray strand? Nothing can escape the keen eyes and experienced hands of a quality control expert!

Video from: Edelrid

Sample testing

When it comes to checking the compliance of ropes with the specified characteristics, a sample is taken from each batch and break-tested according to the appropriate standard. Some manufacturers may have their own additional requirements. For instance, Edelrid conducts non-mandatory cut resistance tests of their invention.

To learn more about standards and relevant tests, refer to the appropriate standard documents: EN 1891 for (semi-)static ropes and EN 892 for dynamic ones.

Dynamic ropes testing according to EN 892 standard at the Edelrid test bench.

Videos from: Edelrid,WeighMyRack

Cutting, middle marking, and labeling

Cutting

After the batch has passed quality control, the rope is cut to the required lengths, which can vary widely. Sections range from 30, 40, 50, 60, 70, 80 meter coils to 200-meter spools. Interestingly, some manufacturers note that the actual length of the rope may slightly exceed the one stated on the packaging. For example, Sterling Rope “adds” about 2% to the stated length of their dynamic ropes, allowing for a small margin to account for potential shrinkage.

60 Meters officially, but 62.1 in fact. Satisfying details from the Sterling Rope factory.

Image from: sterlingrope.com

To prevent the sheath and core from fluffing up, the rope ends are melted. This process is carried out automatically through ultrasonic cutting or manually using a thermal blade.

Automated ultrasonic rope cutting.

Videos from: Tendon, EpicTV Climbing Daily

Manual cutting and melting of rope ends.

Videos from: Tendon, Cousin Trestec

Middle marking

At the same stage, some ropes (mostly dynamic coils) are middle marked, usually in the form of a black indelible strip that “divides” the rope in halves. Middle marks are applied automatically and, if necessary, finished by hand. These are useful for quickly identifying the middle of the rope. However, it is important to take into account that such factory markings become irrelevant and even dangerous as soon as the user shortens the rope unevenly – at one end.

Middle mark application.

Videos from: Decathlon, WeighMyRack

A separate mention is required for bicolor and bipattern ropes, both representing alternative ways of marking the middle of the rope.

Bicolor ropes

In bicolor models, the rope halves differ by the color of some of the sheath yarns. This not only allows for finding the middle of the rope by the change of color but is also useful for differentiating halves when working on a doubled rope. The downside of most bicolor models is the lack of contrast between the halves of the rope.

“SuperStatic2 Bicolor” rope from Sterling rope. You can see how one part of the rope has black sheath yarns, and the other part has colored ones. By the way, static bicolors are pretty rare.

Image from: andersonrescue.com

Technically, the color change occurs at the braiding stage. The process involves stopping the braiding machine and replacing some of the sheath bobbins. In this case, yarns of one color are spliced with yarns of another color. The joint does not lose strength and is almost invisible. But such production is characterized by low speed and high labor intensity, which significantly increases the cost of producing bicolor ropes.

The splicing of differently colored sheath yarns with an “air splicer”. Both strands are inserted into the device and reliably intertwined by the force of compressed air. Excess protruding fibers are removed if necessary.

Image from: sterlingrope.com

Bipattern ropes

In bipattern ropes (not to be confused with braiding patterns), it's not the color but the arrangement of the yarns of the same color that changes. For example, one half of the rope can have the purple sheath yarns arranged in parallel, while on the other half, they are criss-crossed.

Sterling Rope's "Marathon Pro" bipattern dynamic rope.

Image from: sterlingrope.com

By default, this technology also requires stopping the braiding machine and manual manipulation by the operator. However, there is no need to splice the yarns since only the position of the sheath bobbins in the braiding circle changes. The yarns themselves remain continuous. However, at the point where the pattern changes, small irregularities may be felt, which can easily be mistaken for manufacturing defects. This is just an aspect of the technology that does not affect safety.

Recently, Edelrid has adopted a different tech for its bipattern models. The company has developed a braiding machine that allows for automatic pattern changes within just a couple of minutes, thus significantly increasing efficiency and reducing production costs. For example, in the "Tommy Caldwell Eco Dry ColorTec 9.3 mm" dynamic model, some of the sheath yarns from one half of the rope are imperceptibly braided inside the other half, creating the effect of a complete color change.

Edelrid Tommy Caldwell Eco Dry ColorTec 9.3 dynamic rope

Tommy Caldwell Eco Dry ColorTec 9.3 mm dynamic bipattern rope from Edelrid. Some of the sheath yarns from one half of the rope are imperceptibly braided inside the other half, creating the effect of a complete color change. This magical, contrasting color transition between the two halves makes it easy to determine the middle of the rope, even in the dark.

Images from: backcountry.com, WeighMyRack

Labeling

So, the rope is cut, the ends are melted, and the middle is marked. Now it's time to apply and heat shrink the label with basic information about the rope. In fact, a label for each end of the rope.

End labels are applied to both ends of the rope and contain basic information about the model.

Images from: paracord.eu, edelrid.com

Some manufacturers approach the issue of labeling quite creatively.

Video from: Tendon

Coiling & Packaging

Finally, ropes are to be packed neatly. Longer ones, sold by the meter, are simply wound on spools, while shorter ropes are coiled using special machines. Unlike the past when no one paid much attention to coil formation, today manufacturers fiercely compete in the quality of their coiling machines. A proper coil should be free of twists and overlaps, ideally allowing users to climb and belay straight out of the package :)

On the left is the Tendon "Twist Free" rope coiling machine. On the right is Edelrid's patented "3D Lap Coil".

Videos from: Tendon, WeighMyRack

After winding or coiling, each rope is additionally weighed. If a deviation from the norm is detected, the rope is discarded. The ropes that have passed this final inspection are packaged, equipped with instructions and prepared to be sent to stores.

Packaging of coils and spools for shipment to us, the users!

Videos from: Decathlon, Marlow Ropes

IS THAT ALL?

Well, I would like to say so… But, of course not!
I’ve left out some of the more specified production stages, such as the processing of old ropes into raw materials, as well as the stitching of end loops for static ropes. So, there will be something to tell you in the following materials :)
Which means – see you soon!