UKH

I know the answer really, but I’m guessing this needs replacing? I just use it for sport climbing.

Not sure how it happened, but it’s been in the car so probably had something pressing against it in the boot.

In reply to James Malloch:

If you can open the crack up a bit for access then EPP glues very well with cyanoacrylate. It won't break in the same place again if you get good glue coverage and can fit the parts back together like a jigsaw.

Your call, it won't be like new.

Jk

In reply to James Malloch:

Don't mess around with something that's there to save your life. 100% needs replacing 

In reply to James Malloch:

What @andypeak said. Replace it.

Using it in its current state, or gluing it, means your precious brain is more likely to be damaged if something impacts the helmet. Not worth the risk.

In reply to James Malloch:

I like your new hanging basket you've got there, very cool!

In reply to James Malloch:

Suspicions confirmed, thanks. I’ll pick one up this weekend.

In reply to Andypeak:

Waste not, want not!  OP should repair it!

Then give it to someone he doesn't like

In reply to James Malloch:

If the crack in that helmet can successfully be glued (as suggested above), then you'd think that it should be as good as new.

I'm not familiar with modern helmets. Are they supposed to be able to deal with strikes from sharp objects? Or 'just' strikes from blunt objects?

In reply to James Malloch:

I got a new one yesterday. Luckily they still had the black ones in outside (I’m not a fan of the white Sirocco).

I did wonder if gluing it could work as you can prise the crack apart okay but better to be safe than sorry. 

If anyone has a use for the old one then I’m currently in Sheffield for a few days and you’re welcome to it.

In reply to abcdefg:

You might think it would be good as new but it won't. It may be good enough for the vast majority of impacts, but you'll never know until it's too late.

The glue will not act the same way in an impact as the original foam and will distribute the load to your head differently even if it's not directly at the point of impact. 

The UIAA 106 standard does describe a 'penetration test' which includes a conical 3kg impact mass: https://www.theuiaa.org/documents/safety-standards/Pictorial_UIAA106%20Helm...

In reply to James Malloch:

Years ago a friend kicked their climbing helmet off the top of a multi pitch climb on Cadair Idris.  We by chance walked past it returning to our campsite. A month later he was seen climbing with two strips of gaffa tape holding the helmet together.

In reply to jkarran:

Sorry, I call total bullshit on that. First, you are likely confusing the different plastics used in helmets.

Second, even normal PP is really difficult to glue using cyanoacrylates for various reasons, at least without using a primer first, and while extruded PP might be a teensy bit better in that regard due to its extrusion and surface properties (or not!), I wouldn't really trust it anyway.

Even cyanoacrylate glue manufacturers readily acknowledge that PP requires a special formula glue with an oxidising primer.

The shear strength of the cyanoacrylate bond would likely be pretty low, which is not a good thing in a helmet that might experience high shear strengths when hit on only one side of the glue‑bonded crack.

Glued bonds can be difficult and they wary, some glues can even damage the surfaces some types of plastic by outgassing. Your generic advice to "just use some superglue!" without stating the exact glue for the exact plastic type is just totally dumb...

In reply to Frank R.:

However bad the bond may be on paper, in my practical experience it ends up stronger than the surrounding foam, presumably because of the interlocking bits of the break but even clean cuts glue well. I've tried it plenty of times with PP model aircraft, it's never the glue joint that fails subsequently. As I see it a repaired helmet is better than a binned and not replaced helmet, they're expensive. Not perfect but I didn't say it would be.

Jk

In reply to jkarran:

Yes, you even acknowledged that. The biggest problem I had with your post from a material science amateur perspective (myself) was that you made it sound like it always works well, without even mentioning the very specific cyanoacrylate glue and whether you ever used any primer specific to PP bonding, because glue bonds aren't really that simple. Even if you were actually right, model aircraft doesn't equal helmets, do they?

Because there are literally dozens of cyanoacrylate glues (some including primers, some not), many of them not really (or much less) suitable for that exact plastic bond. As explained by their very manufacturers. And that's even before getting into the bond strength itself.

Frankly, as somebody doing model plastic aircraft, you should be really pretty well‑versed in all the various material bonding options, but that doesn't seem the case to me, sorry.

And I won't even start to get into what pretty different forces something like a plastic wing of a model airplane might have to encounter as compared to the actual vector forces on a helmet...

In reply to Frank R.:

I've never been the least bit picky about the specific glue, it makes a reasonably strong joint in a reasonably weak material, at least that has been my experience with no effort put into process or material choice. If the foam were stronger I'm sure it would start to shine a light on the bond but it's not, it's foam.

Jk

In reply to Frank R.:

Not wanting to get in a discussion about glues, but the helmet in question uses Expanded Polypropylene (EPP) as the major part of its construction.

Extruded PP?  Do you mean Expanded Polypropylene?

In reply to jkarran:

I think you are correct in saying that the glue could well end up being the strongest part of the helmet. However, that doesn't necessarily mean that a repaired helmet will be stronger or safer as a total system.

When whitewater kayaks crack, people often make the mistake of welding them back together using excessive amounts of plastic. This means that when you next hit a rock in your kayak, the repaired section is too rigid, and does not flex to absorb the impact. The result is that the energy is absorbed by other areas of the boat, causing fatigue. For a bigger impact where "something's gotta give", the rigid repaired section will usually break instead of bending.

As someone else said, the repaired helmet will respond to load in a totally different way to the original helmet, and I would argue that the extra rigidity would likely result in more energy from an impact being dissipated in the wearer's skull instead of in the helmet, and a lower failure load.

In reply to James Malloch:

I feel like joining in this game of uninformed opinion and speculation, so here goes. 🙂

My take is that if you glue the helmet it will be not as good as when it was new. The question is, how much does the drop in performance matter? What are the chances of being involved in an incident in which this drop in performance makes a difference? I'd say pretty damn low. The vast majority of the time the helmet will be adequate. In more serious incidents you're fooked anyway. So that leaves a very narrow band of incidents in which the drop in performance actually matters. Replacing the helmet means paying a decent sum to protect against an extremely unlikely event. We are all limited by budget, so would that money be better spent elsewhere? A new cam might prevent you falling so far and banging your head in the first place...

In reply to cacheson:

I don't disagree.

I think 'totally' overstates it. Obviously the repaired region won't behave exactly the same as the surrounding material but glued EPP is still flexible and soft, a thin film of glue doesn't significantly change that. It's worth remembering these things are already full of major discontinuities in the material stiffness in the form of big holes which nobody worries about. It's a bumper for your head, it just has to get and stay between your head and the rock while it crushes.

Replacement is the best and obviously most expensive option but my argument is it's still a serviceable bit of kit with a repair in it, not like new but still pretty good.

jk

In reply to Hooo:

Unlikely, but high consequence. Brain injuries aren’t much fun.

The OP said they use the helmet sport climbing, so a cam would be a weird use of money if their budget is very tight (which they haven’t suggested it is) and not much use against a falling rock.

In reply to Hooo:

Another uninformed viewpoint from me. A helmet is such a versatile form of protection and approximately the same cost as, say, a cam that in the fantasy situation where I could only afford one I'd get the helmet. Useful for exposed walking, scrambling, winter as well as rock climbing. In fact it's often the only protection for someone going solo.

I imagine a glue might be quite strong if it formed a continuous layer which infiltrated into all the cavities exposed in a crack in the EPP foam.

Personally I'always replace a damaged helmet unless none was available. But if I couldn't access a climbing helmet I'd even consider another type eg skiing as well a repaired helmet. I've definitely escaped serious head injury twice due to my helmet.

In reply to James Malloch:

Is this peak UKC, suggesting glueing a helmet back together is ok?! Are we going to hand stitch a cut belay loop back together next week? 😂

In reply to jezb1:

I wouldn't, they do quite different things (helmets vs belay loops).

jk

In reply to abcdefg:

There are specific (and dull) standards you can look up. Very very basically helmets fall into 2 types

• Resist some puncture, resist bluntish objects from above like falling bricks, chin strap not too strong so no strangulation risk when hooked on scaffolding etc, not especially concerned with multiple impacts as the chin strap isn't very strong anyway. Tend to be taller on the head, hard surface to resist wear and tear, can fall on floor and get kicked across the canteen without damage, white so you can write your name on the front (maybe a witty expletive laden slogan too on the side) with a sharpie pen and invalidate the warranty but likely nobody will care, not sure that's defined as a requirement in the EN standards though 
• No huge puncture concern beyond sharp rock, resist bluntish impacts from above and from sides, strong chin strap to stay on after first impact, concern for multiple impacts such as bouncing down a cliff. More compact on head, sometimes less robust.

Climbing helmets fall into the second category, industrial ones are confused about their identity and some (e.g. petzl vertex) let you adjust the chin strap to be weak or strong. Vertex may be one of the most robust helmets out there but they're really not so great for recreational climbing.

In reply to jezb1:

But that's just because you're a sponsored hero sucking at the teat of "Big Climbing", so you would say that wouldn't you? ;⁠-⁠) 

<I think by adding some conspiracy theory to this, NOW we're at Peak UKC!> 😆

In reply to TobyA:

In my dreams 😂

In reply to oldie:

The choice I described wasn't between a helmet or a cam, it was between replacing a useable helmet with a marginally better one, or buying a different piece of safety equipment. Not a cam, because the OP is a sport climber. Something that makes sport climbing safer. Doesn't have to even be climbing related, maybe the OPs cycle helmet is getting on a bit and they'd be better off replacing that. Or something. The point is that replacing that helmet is expensive for a marginal gain. Maybe the OP should buy a more robust helmet, as a helmet that got broken in the boot of the car doesn't sound very reassuring to me.

In reply to jezb1:

Don't the lovely folk at Outside support you/your videos? Semi-sponsored hero? Pro-deal discount hero? 😄

In reply to oldie:

I am, at great difficulty, forcing myself to remain silent and not join in…

But I might be designing a test rig…

 

In reply to Hooo:

This is getting weirder with each passing post. So now, instead of replacing the broken helmet, you're wondering if they should instead replace something else that isn't broken?

In reply to Stuart Williams:

I'm suggesting they could be better off patching up the helmet and spending the money on something else. Not replacing something that isn't broken, something that will have a better chance of improving their safety.

In reply to Hooo:

I’m with Hooo. I’ve almost certainly had my life saved 5 times by helmets -2 motorbike, 2 cycling and 1 climbing. All visibly cracked, deformed and replaced, and me concussed and hospitalised with other bits bent or broken. But as not all helmets are equal, nor all damage nor all accidents, I agree there’s a sliding scale of protection on offer from the lightweight to the hefty and we already place our bets. I choose to wear a Boreo as I’m accident prone, and clumsy packing gear to boot so a tougher helmet suits me, but I’m under no illusion it makes me invulnerable. 

The poorest or most compromised helmet will still be better than nothing, saving you some scrapes or maybe reducing the level of a concussion if you’re lucky. And even the best may be totally useless in a catastrophic groundfall (or falling fridge) case. For most ‘helmet hits’ there’s really a fairly narrow survivable range where the helmet helps beyond anything but bandaid injuries and we shouldn’t kid ourselves how effective they are. Would I use a repaired helmet? If I’d repaired it, probably. Would I use an ultralight helmet? Would I wear a cycling helmet to climb? I think I’m realistic about the risks and benefits, the materials (I was a materials engineer for a while (and more importantly, built model aeroplanes)), understand helmet design and don’t place too much confidence in the performance of new helmets to begin with. So I wouldn’t automatically bin a cracked helmet, but I’d think hard about it on a case by case basis. 

In reply to Hooo:

Sorry, you didn’t mention that the “getting on a bit” bike helmet was also broken.

Mind you, the OP also didn’t mention that they could only afford to replace one of two broken helmets so it’s good of you to remind them. We probably need a picture of the damage to the bike helmet before deciding which one to glue though.