Sunscreen
Be afraid, carelessly applying sunscreen near climbing gear could weaken it by 40%. Or so says a recent Instagram post by the International Climbing and Mountaineering Federation (UIAA). While sunscreen is rated by 3 letters, SPF, we felt that the statement by the UIAA deserved a two letter rating, B.S.
We started digging into the research and couldn’t find any sources that agreed with the post by UIAA. We went thru the article they cited in the instagram post. Published by UIAA SafeCom, we felt it was full of logical fallacies and definitely didn’t make a convincing case that sunscreen or any ingredients used in sunscreen were actually harmful to the fibers used in climbing gear. AND THEY DIDN”T EVEN BREAK TEST ANYTHING EXPOSED TO SUNSCREEN.
Spending time in the sun at high altitude, like climbers and mountaineers do, means a lot of UV exposure. Sunscreen and protective clothing is what the experts recommend to reduce the risk of skin cancer from UV exposure. We feel that discouraging sunscreen use is against the best interest of climbers, especially when there is no evidence that it has any affect on climbing gear.

At HowNot2 we believe in breaking gear fear, so we reached out to our audience to see if anyone was actually worried about sunscreen damaging climbing gear. Out of the 1200 people who responded to our Instagram pole, 41% thought that sunscreen would weaken a rope. That really surprised us. Time to break some gear fear.
With the help of our Dermatologist, Andrea, we assembled 8 sunscreens that contain every ingredient commonly found in sunscreens worldwide. Based on our audience feedback we decided to expose a rope to the sunscreens for a month. During that month we soaked the samples and allowed them to dry, soaked them again and kept them moist for 2 weeks and soaked them again and exposed them to UV light for 15 hrs over 3 afternoons.
The rope was a 9mm Sterling Safety Pro with a nylon core and nylon sheath. While it was soaking in sunscreen, our engineer Chase was working frantically on designing and getting an improved diverter fabricated. We have tested a single brand of sunscreen on ropes before, but we tested it knot to knot, with the segment exposed to sunscreen in the middle. Our thought was if the knots compromised the rope more than the sunscreen it wasn’t a concern. To really put this myth to bed we were going to use diverters to achieve the ropes “full strength”.
Wrapping a rope around and around a thick metal cylinder prevents any pinches or bends in the rope from breaking it below “full strength”. Pinches and bends caused by things like knots and carabiners. Since we don’t know anyone who climbs or works with big metal cylinders at every point a rope touches, we don’t feel testing with diverters is representative of the real world. But it will allow us to see if the rope is weakened at all by the sunscreen.
Testing Time! Sterling Safety Pro is rated to 19kN. In our control tests the rope broke in the back of the diverter at over 20 kn. If any of the sunscreens had damaged the ropes in any way we would expect to see it breaking in between the diverters where the sunscreen was applied and/or results less than 19 kN. We saw a few samples break in the sunscreen affected area at over 20 kN. And one sample broke at slightly less than 20 kN but it failed in the diverter.
The UIAA post mentioned alcohol (denatured alcohol is used in some spray sunscreen) and Avobenzone as chemicals of particular concern. So we had prepped samples in the same way with those chemicals in the highest concentrations possible. Those samples still broke above 20 kN.
We sure didn’t see any evidence in our testing of 30 samples to suggest that sunscreen weakens climbing gear made out of nylon in any way. Knots on the other hand weakened the SafetyPro by almost 30%.
Moral of the story, worry about the things that actually happen, like skin cancer. Use Sunscreen! If you get on your gear rinse it off, not because it’s dangerous, because it’s gross.
https://www.theuiaa.org/uiaa-safecom-answers-your-questions-suncream-and-climbing-gear/