Hej!

I visited the the Historiska and Armé museet in Stockholm and I wondered about the thickness of all those displayed helmets - mostly from vendel / early viking period.

I tried my best to see the helmets as close and from as many angles as I could without being treated like a thief.
All seemed to have plates with thickness c. 1-1,5 mm

Even their nasals and cheeek-guards displayed much the same thickness - or maybe weakness.

My battle helmet (vendel style) is c. 2 mm thick, only cheek plates are 1,5 mm and nasal is 3-4 mm thick..

1. So am I right in my "eye only" measurement - that vikings/vendel used those slimmer helmets with thickness c. 1-1,5 mm?
- so the helmets were lighter and warriors could be bit more agile
- that would also explain the ability of some warriors to cut through the helmets of opponents (even with swords) as is known from sagas...

2. Am I right in my second guess that today helmets use thicker helmets only for some safety reasons?
- they are not based (in this feature) upon archeological evidence

Hi G!
It's great that you take the time to study our national treasures. I hope you had a great time in Sweden!
The finds from Uppsala högar especially are royal graves of particular richness.
I remember seeing photos in books as a kid and thinking these look kind of cool. But they are simply mind blowing up close. The detail, the craftsmanship. No wonder so many of us historically inclined fall in love with them and their British counterparts like the Sutton-Ho and others. It was simply an age of wonder.

Modern day made iron age style helmets need to be thick to withstand blunted steel or rattan blows. It's a safety issue most armourers follow these days even for purely art reproduction pieces because who knows what a crazy collector/ re-reenactor will think of doing with it.

I haven't had a chance to actually measure any of the Vendel helmets in person either, just admire them though the glass in the museums.
Some of them look thin yes, unless you count eyebrows and ridges of course which are very thick.
But what we see today is probably thinner material than what it once was when they were brand new and outer layers of metal visible thorough the glass at a museum might be thinner than the rest. That doesn't even factor in eye measure through glass sometimes quite a distance off the object.

I've mainly been studying what photos there are of the norwegian Gjermundbu helmet in detail and the plates on that one seem to me to be about 1,5 mm thick today, making overlaps about 3 mm. The glasses are very thick though, probably 3 mm or even thicker and the cross over the skull is D-shaped and very thick, perhaps as thick as 6 mm at the top.
But this isn't Vendel age (approximately carolingian age), it's from late viking age. An age of heavier and more practical armour perhaps?

I've seen weights on Normand helmets that seem to indiacate they'd be about 1,2-1,5 mm in average if it was brand new, but again rusted away material is hard to gauge. Just look at some swords that are barely wafer thin today while others are thick and still seem sturdy enough to cut with. They might once have been the same when they were new.

I would be very interested if there is scientific papers on the subject. Perhaps there is research done on the Vendel and Valsgärde helmets that list or extrapolate plate thickness?

Agreed with Sean. You'd need a solid hit with an axe or a heavy bow at close range to penetrate helmet plate that is thicker than 1mm.

Sure about what?

Sure about solid hit :-) which can go through helmet which is more than 1 mm thick.

According to what I saw (I have done no tests in that):
1 mm can be deformed by sword and one handed axe can go through (maybe not in the first attempt)
1,5 mm can stop sword and one handed axe can deform it easily and after a time perhaps penetrate, daneaxe (two handed) can go through easily
2,0 mm can stop sword and one handed axe, it can withstand dane axe (=only really hevy blows can go through)
2,5 mm can stop almost anything :-)

in all that I am talking about BLUNT weapons..
.

Another thing worthy of note is that those helmets are all from time before "dane axe" becomes widespread - so, basically, to get through to the wearer's head you would have to manage a very precise hit at a very precise angle. I would say it is more likely to manage a stab into the eye than that. Note, that decorative plates, especially, if backed by leather backing, as it is known to have been at least on some helmets, provides additional layer of composite protection. And even if you actually pierce the helm, it is not likely they they would have been placed directly on the head, most likely there would have been a cap of some sort underneath to reduce the effect of the blows...

One thing I always say to people when talking about helmets- They don't make you invincible. I liken them to slightly strong building site PPE, hard hats. A helmet that isn't going to stop a full on blow from anything, that's down to your skills and abilities, its just there to give a bit of extra protection in a very hazardous environment. In presses I very often find armour is more useful protecting you from excited comrades....

I'm just having a late 17th cent helmet made and its going to be the same thickness as an original from Littlecoat. Way thinner than most re-enactors use. Its a crumple zone really, not a brick wall.

We have no idea how thick most helmets were. Most have had centuries of corrosion and have been "restored" after they were uncovered. The only helmets that we can be pretty sure are still close to their original thickness are the ones that were painted during the time in which they were being used, have minimal corrosion today, and still show some of the original paintwork.