Secure rock anchors are fundamental to safe climbing. In recent years, conversations around rebolting, stress corrosion, bolting ethics and route safety have become more fervent and widespread. A year ago, the UIAA Safety Commission, a voluntary body dedicated to developing international safety standards for a wide range of climbing gear and equipment, including rock anchors, was invited by local authorities in Kalymnos, Greece to host a bolting workshop as part of its annual safety meetings. These took place in early May 2026.
Kalymnos with its dramatic, photogenic limestone walls, steep tufas and amazing climbing culture is a veritable climbing paradise. However, local exposure conditions are highly aggressive, and some sectors effectively behave as microclimates. As a consequence, local authorities were keen to learn more from the UIAA’s decade long research into bolts and stress corrosion cracking as well as how best to take on the challenge of rebolting a vast number of routes.
Recent discussions surrounding anchor failures and corrosion have raised urgent questions about long-term route maintenance, materials, environmental exposure and local oversight. The UIAA’s ability to act as a neutral technical voice, bringing together local authorities, bolters, route developers and community representatives, was viewed as an important contribution during a difficult moment.
“The bolting challenge in Kalymnos is very big. We have almost 5,000 routes all over the island. About 1,000 of these routes are more than 20 years old and these routes start to have old material and are open to corrosion. We have to prioritise rebolting these 1,000 routes. The UIAA meeting in Kalymnos is crucial as it is a critical moment for the island as we move from stainless steel to a better material for longer-term sustainability. The UIAA meetings will help us take the right decision on the direction to take.”
– Aris Theodoropoulos, Rebolt Kalymnos
Aris Theodoropoulos (Rebolt Kalymnos) and Fred Campos (UIAA Safety Commission). Photo credit: Rainer Eder/UIAA
UIAA Safety Commission President Lionel Kiener opens the Rebolting Workshop.
Photo credit: Rainer Eder/UIAA
Registration at the UIAA Rebolting Workshop.
Photo credit: Rainer Eder/UIAA
Crag Inspections
Ahead of the bolting workshop, members of the UIAA Safety Commission carried out two days of crag inspections across Kalymnos. Their work included pull testing, visual inspections and observations related to corrosion and anchor materials.
SafeCom examined a wide range of hardware:
- 304 stainless steel anchors
- 316 stainless steel anchors
- Galvanized carbon steel anchors
- Titanium anchors
- Unknown alloys
One aspect which was already well defined, is that corrosion is highly complex and deeply dependent on local environmental conditions (among others such as bolt style, alloy, and manufacturing quality). Wind exposure, air quality, humidity, sun, shade and rock composition all influence long-term bolt performance.
UIAA experts have also increasingly observed that poor bolt placement is also a major issue. In some cases, anchors failed at very low loads due to rock quality or placement conditions. This issue is perhaps less widely discussed than those related to corrosion. While many discussions focus heavily on the material component, but installation technique, assessment of rock quality and long-term route management may be equally critical. Findings from the crag inspections in Kalymnos are currently being analysed. The UIAA report will be published once the laboratory analysis of all collected samples has been completed.
A video guide on how the UIAA inspects routes will be available in the summer of 2026.
Stephen Gladieux, UIAA Safety Commission, discussing corrosion.
Photo credit: Rainer Eder/UIAA
Tools in place for the Rebolting Workshop practical session.
Photo credit: Rainer Eder/UIAA
Participants learning new skills during the UIAA Rebolting Workshop.
Photo credit: Rainer Eder/UIAA
Rebolting Workshop
The Rebolting Workshop itself was considered a major success. It welcomed approximately 40 participants, from more than 80 applications received.
The format of the workshop included a theoretical session on various types of corrosions, ethics, anchor selection, the evolution of UIAA Standard 123 and related topics and practical sessions on the crags. The programme was designed with elements for both beginners and experienced bolters. Sessions around bolt removal techniques were particularly valuable for many participants.
Below are key extracts and takeaways from the presentations given:
Inside UIAA Standard 123
UIAA delegate Fred Campos (Brazil, CBME), led a session which addressed key points from UIAA Standard 123 and the major safety improvements introduced in recent updates. He focused on how the UIAA Safety Label guarantees compliance with rigorous testing requirements that go beyond existing EN standards, covering mechanical strength, corrosion resistance, welding integrity, material traceability and quality assurance.
Campos highlighted the growing understanding of atmospherically induced stress corrosion cracking (AISCC), which became a key driver behind the revision of UIAA 123 version 4. Research and laboratory testing demonstrated that common stainless steels such as 304(L) and 316(L) can still suffer dangerous cracking under certain environmental conditions, especially when chloride salts and humidity combine. The updated standard therefore introduced corrosion classes and accelerated laboratory testing to simulate years of environmental exposure.
How anchors need to be treated as complete systems rather than simply selecting a corrosion-resistant material was a significant message relayed. Production quality, welding procedures, manufacturing and installation stress, and material traceability all influence long-term durability. Version 5 of the UIAA Standard strengthened requirements for welding quality control and material certification, reflecting lessons learned from field failures and recalls. Campos, one of the key members of the SafeCom working group on this topic, closed by reinforcing that anchor selection must be evidence-based, conservative and adapted to local environmental conditions in order to ensure long-term climber safety.
Slide from the presentation on Stress Corrosion
Photo credit: Stephen Gladieux/UIAA
Slide from the presentation on inspecting rock anchors
Photo credit: Per Forsberg/UIAA
Corrosion in rock anchors
Stephen Gladieux (United States, AAC) introduced corrosion in rock anchors, exploring the technical and environmental factors that affect the safety and longevity of climbing anchors. Different forms of corrosion are examined by the UIAA, including general corrosion, galvanic corrosion, pitting, crevice corrosion and the particularly dangerous stress corrosion cracking (SCC) and sulfur stress cracking (SSC).
He emphasised how the style of anchor (i.e. the nature of how it is intended to function) is a huge player in determining susceptibility to different forms of corrosion. All anchors have some level of residual stresses from manufacturing, but some anchor styles intentionally create larger tensile stresses in the shaft that exist from installation until the end of the bolt’s life. The thermal history of the anchor, from raw material, to heat treatment, to welding can be an enormous influence as well.
Stephen also highlighted how a relatively small amount of corrosion in the back of the hole can prevent the anchor from functioning as designed. An example of this is where corrosion between the collar and the wedge on a wedge bolt creates more friction than there is between the collar and the rock. This scenario prevents follow-up expansion, and can lead to dangerously weak bolts in steep placements that can be difficult to recognize. Any corrosion on an anchor means it is not the correct choice for the area long term.
Anchor failure is often linked not only to the material itself, but also to environmental conditions and installation methods. Moisture, chloride salts, sulfur sources and poor washing conditions can accelerate deterioration, especially in coastal or humid climbing areas. This presentation highlighted how hidden corrosion can develop beneath hangers, inside pits or in resin-sealed areas, making inspection challenging.
The presentation also outlined mitigation strategies, including careful material selection, use of higher-grade stainless steels or titanium, regular inspection programmes and detailed record keeping of anchor installations and replacement cycles.
Tools in place for the Rebolting Workshop practical session.
Photo credit: Rainer Eder/UIAA
Drilling technique practice in Kalymnos.
Photo credit: Rainer Eder/UIAA
Inspection and selection of rock anchors
Per Forsberg (Sweden, SKF) explained the framework for selecting, inspecting and maintaining rock anchors in climbing environments. He used the previous day’s inspection on Kalymnos as a case study. Forsberg emphasised that anchor safety depends on understanding corrosion risk, rock quality, environmental exposure and patterns of use. The UIAA corrosion classification system can help route developers and rebolting teams assess appropriate materials and identify areas at risk from general corrosion or stress corrosion cracking (SCC).
Forsberg highlighted how older 304(L) stainless steel anchors should be replaced urgently, while 316(L) anchors require continued monitoring. Factors influencing anchor lifespan include chloride exposure from the sea, rock chemistry, rain washing, temperature, manufacturing stress, installation methods and surface contamination. The presentation also referenced atmospheric corrosivity mapping and stainless-steel selection guidelines to support informed decision-making in different environments.
In terms of inspection procedures, the importance of identifying anchor types, installation age and previous warning signs through markings, guidebooks and visual checks were explained in detail. While anchor testing is not considered standard practice, techniques such as pull-out testing (at non-destructive load levels and/or to failure), dye-penetrant testing to screen for cracks on representative samples, and chemical screening (e.g., a molybdenum reagent test to differentiate unmarked, aged 304/A2 from 316/A4 components) can support investigations and long-term monitoring.
Bolting ethics
The presentation “UIAA Re-Bolting Ethics & Core Tenets” explored the ethical principles guiding the replacement and upgrading of climbing bolts. Marc Beverly (United States) and Stephen Gladieux explained that re-bolting involves balancing modern safety needs with respect for the original character and style of climbing routes. This touched on the ongoing debates between preserving first-ascent ethics and improving accessibility and safety for today’s climbers.
A strong emphasis within this mantra is placed on climbers creating and maintaining their own ethical standards through local consensus, transparency and documentation of changes. Environmental and social responsibilities, including erosion control, wildlife protection and Leave No Trace principles, are also discussed. Responsible “like-for-like” bolt replacement and evidence-based upgrading remain widely accepted best practices within the climbing community.
Photo credits: Rainer Eder/UIAA
Quotes and Feedback
“It was a fantastic aggregate of many events: led by a warm welcome from the municipality and Christos and extending into the strategic discussions about the future of climbing and rebolting which made a big impression on the international UIAA SafeCom team. Everything was organised incredibly efficiently and professionally for inspections and then for the presentations despite the short turnaround time. The positive spirit of all workshop participants and their goodwill to work all together to tackle the various topics and help develop sustainable solutions for the future was a major positive. The discussions also extended to rescue where ICAR representatives had the chance to work with local teams and outline future ideas. All of this in parallel with UIAA SafeCom meetings with manufacturers and laboratories from across the globe.”
Lionel Kiener, UIAA Safety Commission President (Swiss Alpine Club)
“We covered a lot of subjects, experiences, and specific techniques for removing bolts of different types. The focus was on how to safely use the same holes for new bolts rather than encouraging the drilling of new holes. We also shared experiences we have with conservation built over many years, whether social trails, dealing with adjusting or making routes safer for a modern climber, or techniques and materials which will help bolts survive in this highly corrosive environment.”
Stephen Gladieux, UIAA Safety Commission (American Alpine Club)
“I am here to improve, learn new things and safety is the most important thing. Over the winter I bolted routes in Kos and I want to be sure that what I am doing is super safe and bomb proof.”
Workshop Participant
“I am grateful to have taken part in this workshop, where I met people from all over the world who share the same passion and many ideas and experiences that we were all able to exchange. All the trainers were amazing and truly inspiring, always willing to answer all our questions, and making the whole process incredibly engaging and interesting. It was very unique experience that I will never forget, and I leave with more knowledge, curiosity and friends!”
Workshop Participant
“The UIAA was delighted with how the week of activities unfolded. These type of events are incredibly challenging to put together demanding a significant amount of volunteer time and expertise. A huge thanks goes to everyone involved. They are also deeply rewarding as outlined by the feedback from the UIAA Safety Commission and the participants. The UIAA will look at developing similar concepts in the future and more importantly continuing to make this vital information available to climbers and bolters worldwide.”
Andre von Rotz, UIAA CEO
“The event was awesome – learning from experts worldwide and being able to ask questions to the level of depth you want to go has been really cool and getting hands on experience. Its impressive to see the engagement from the community here.”
Cole Patterson, Arc’teryx, Canada
“I saw that the workshop was happening. This represented a great chance to learn about a new subject and I knew I would be around people who are world-class in what they do. I was not just about the bolting but everything about the experience I got from these days.”
Workshop Participant
“Knowledge and sharing experience are the best way to improve our business. All of us who bolt climbs need to dive deep into the world of bolting – a UIAA workshop is key.”
Workshop Participant
Future Bolting Workshops
For future events, the UIAA is considering evolving the concept particularly given the challenges of creating workshops accessible for a wide range of experiences. One suggestion was for the UIAA to focus more on “training the trainers” or training experienced bolters who can then transfer knowledge regionally, rather than providing basic training to large numbers of individual bolters.
Words of appreciation
The UIAA thanks all of those who participated in the event for their important contributions. The event would not have been possible without the support of the Municipality of Kalymnos, the Hellenic Federation of Mountaineering and Climbing, Rebolt Kalymnos, and the UIAA-certified anchor manufacturers who supported the practical sessions. And above all thanks goes to the many dedicated volunteers of the UIAA Safety Commission for leading the workshop and the field sessions.
Key Resources
The UIAA Safety Commission has provided climbers and bolters with a wealth of material much of which is linked below. Commission members are currently working on a dedicated rebolting guide – which will cover techniques, funding, inclusion, communication, social media pressure, ethics and other aspects
Across the UIAA social media channels, a number of videos – shot in Kalymnos – and covering the rebolting process will be published over the coming months.
- UIAA Rock Anchors page
- UIAA Safety Standards
- UIAA Standard 123
- UIAA Watch Your Anchor Warning
- UIAA–DAV Bolting Booklet
(Note: this booklet is slightly outdated compared to the latest UIAA 123 work — an update is coming soon)
