Material knowhow

  1. ISA Slackline Gear Standards

    isa slackline certification

    Certified Slackline Gear

    The International Slackline Association (ISA) has started to certify highline-gear. Some people are wondering what the advantage of a certification might be. But before answering, let us ask you a question: Would you buy climbing gear that is not certified? Most climbers would not.

    But let us start explaining how gear can become certified. First, the ISA is in discussion with different slackline-brands to decide what the gear in question needs to fulfil. This includes:

    • Minimum Breaking strength
    • A manual that is easy to understand and explains well how the gear needs to be used
    • A clarification after how much time the gear needs to be replaced
    • Depending on the gear some further tests like e.g. slippage-test for weblocks, etc.

    Those standards are based on experience from highlining of the last decades, different studies led by the ISA, private people or companies, experience from the climbing world and the incidents and accidents that have happened in the slackline-world so far.

    Once a standard for a certain piece of gear has been decided, the company needs to send their gear to a neutral tester. This is SIEBERT CONSULTING (Walter Siebert, siebert.at) who then tests the gear according to the standard. The manual will be checked by a team from the ISA. Once the gear has successfully been tested and has fulfilled all the required standard, it will be officially certified slackline- or highline-gear.

    But what is the advantage for you as user? So far (March 2020) there is almost no tested gear on the market. But this will change over the next months and years and it will become a standard.

    • When buying certified gear you will know that it is safe and tested by a neutral party. In the manual you will also be able to read how it needs to be used, about the lifespan of the gear and at what point it should be replaced.
    • Insurance companies might insist (in future) that only certifed gear will be used to get an insurance covering.
    • Access: Often when talking to officials about permission to rig a slackline or highline in a public space, you will be asked whether you use certified gear. In future you can answer with yes which will for sure help you to get access to a new place.
    • Gear certification will also help to get acceptance for the sport – it is not unlikely that prohibited areas for highlining will be allowed again.
    • Shows: when offering shows and courses it will help you a lot if you can tell the organizers that you are using certified gear.

    SLACKTIVITY has started with 3 certified products: redTube, seaHorse and the leash – more will follow.

    redTube

    Webbing is categorized into 4 different types, depending on the MBS (minimum breaking strength). The webbing categories A+, A, B and C of the ISA have nothing to do with the categories A, B and C that have been used by SLACKTIVITY for over 2 years now (just coincidence). Here are the ISA classifications:

    • Type A+: 40kN+
    • Type A: 30 – 40kN
    • Type B: 26 – 30kN
    • Type C: 22 – 26kN

    The SLACKTIVITY redTube is the first webbing on the market that can be used as an official highline webbing. It is categorized as webbing Type A by the ISA-Standards. This means, it has a recommended lifetime of 720 days of use. Lifetime is counted as the days that the slackline is rigged. Leaving your line rigged for a week costs 7 days of lifetime, no matter if it is being sessioned or not because UV-light is one of the main factors to weaken your line. Once the days run out, the slackline is no longer safe for highlining. Webbing can becume unsafe much earlier for other reasons like abrasion, cuts, burns or contact with chemicals.

    For permanent rigs, SLACKTIVITY recommends slacklines that have a physical connection between the mainline and the backup. This is e.g. the case with redTube Type B (SLACKTIVITY-classification of webbings with T-Loops). The T-Loop should be connected to a backup-webbing with a knot/connection that holds at least 12kN. Here you can find the breaking strength of different knots of SLACKTIVITY-Webbings.

    Be aware that every redTube sold, comes with a sewn end loop on BOTH sides of the line plus a backup loop on one side of the line. This loop can be used for a direct connection to the anchor point. More information about the use of the redTube as highline can be found in the manual.

    Leash

    Also for highline-leashes there is a new ISA-Standard. And the SLACKTIVITY leash is the first leash on the market that can officially be used on a highline. According to the standard the rings need to have a MBS of at least 24kN. The SLACKTIVITY leash ring is much stronger than the required standard and convinces with a MBS of 39kN at a weight of only 51g per ring. Also the weight of the rings have been limited to 150g in the new ISA standard, because being hit by a heavy ring can lead to injuries. Therefore oldschool leashes with a heavy steel bomber ring will luckily be prohibited in future.

    SLACKTIVITY (Tobi + Sam) thanks to all people from the ISA that have worked hard to realize this standards - we think it is a big step for the slackline sport and his futur.

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  2. Study of breaking strength reduction in highlines caused by UV-light exposure

    SLACKTIVITY (Samuel Volery, Tobias Rodenkirch) has conducted a UV-light-exposition test in a permanent midline that was up for 7 months over summer. The tested slacklines were not in the shade but rigged in full exposition to the sun. Five different Slacktivity webbings were tested:

    uv-test-slackline-webbing

    The main line as well as the backup have been tested. After about 1500 hours in the sun the breaking strength of the mainline has decreased an avarage of about 8kN (=800kg) and the one of the backup has decreased by about 7kN. The complete study can be read in the following pdf document.

    Study of breaking strength reduction in highlines caused by UV-light exposure (pdf)

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  3. Used pinkTube breaking strength test by the International Slackline Association (ISA)

    A piece of pinkTube has been permanently rigged and sessioned for 6-8 months. It has seen between 3000 - 5000 leashfalls and was exposed to the sun for about 2 hours per day. It was located in a forest in France, near streaming water with high humidity. This piece of webbing has been break tested by the International Slackline Association. In the following article you can see the results:

    Webbing break tests Slacktivity pinkTube - ISA

    If you want to find out more about forces that are occuring in highlines, then you can watch the following video. Be aware that highlines rigged with low-stretch webbing and short highlines see clearly higher peak forces compared to high-stretch webbing ones or long highlines. 

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  4. Knots in slackline webbing

    TEAR IT UP

    Knot breaking by SLACKTIVITY

    Tear it up

    Author: Daan Nieuwenhuis
    Break tests: Daan Nieuwenhuis & Samuel Volery
    Pictures by: Daan Nieuwenhuis

    Introduction

    Since a few years the low-tension lines have become more of a standard. This new style brings new styles of rigging, one of these is tying knots in the back up webbing. But what does a knot in webbing actually hold? How does the knot influence the breaking strength of the webbing? As SLACKTIVITY we also had the goal to test out multiple knots to connect our back-up webbing to the mainline in our Type B webbings (redTube & pinkTube). This is done by making a knot in your back up webbing, and connect it to a T-Loop with a quicklink.

    WARNING: Knots can be complicated and hard to check properly. Don’t use them if you’re not 100% sure that the knot is correct, or if there is nobody that has the knowledge to double check it. Even after tying a knot 20 times, mistakes can still happen. Always double check each other rigs.

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  5. Forces in Highlining

    Many people who see a highliner on a highline for the first time, think that the forces are very high, especially when falling into the highline (leash fall). Since the slack ("sag") in highlining is not as limiting as in longlining over ground, most highlines are much less biased and this leads to lower forces than you would like.

    Check out this video and write out of the tests we did:

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  6. Oval-Carabiner vs. Pear-Shaped Carabiner

    Because slacklining is still a young sport and there are still few materials and standards that are geared to the slackline application, material from other applications (from sports and industrial climbing to industrial applications) is used.
    Here in this article it is shown that this is carabiners can be used in a few applications while slacklining. Be aware that you never use aluminum carabiners in your rig. They tend to break under cyclid load. 

     

    This video shows how the carabiner shape affects the breaking load of triangular loads. 

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  7. Forces in slacklining (Ratchet lines)

    The forces that occur during slacklining are composed of the preload force and the weight of the slackliner. This can be both static and dynamic. It is not possible to determine the forces without measuring device exactly - but one can calculate the forces in static slacklining with a formula approximately.

    Here are some basic rules of the forces:

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