I am designing armour for an adventurer and I want to give him something unique compared to the normal soldiers of this world.

My first idea is that this guy has found a method of finishing an iron surface that gives that surface an ultra-low coefficient of friction. It has identical properties to iron except the outer surface is entirely frictionless. The adventurer decided to make a suit of plate armour out of it because he thought it would be cool. I want to know whether this armour will have any benefits or drawbacks compared to steel plate armour.

For context the adventurer will face enemies carrying bladed weapons, mainly swords, and also longbowmen. Also, the palms of the hands and soles of the feet have grip, so that he can move and hold weapons.

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    $\begingroup$ Does this frictionless version iron have friction with itself? $\endgroup$ Sep 3, 2016 at 21:01
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    $\begingroup$ "I want to know whether this armour will have any benefits" -no word about drawbacks, and i can name many. $\endgroup$
    – Mołot
    Sep 3, 2016 at 21:04
  • $\begingroup$ @JarredAllen No it has no friction with itself. $\endgroup$ Sep 3, 2016 at 21:08
  • $\begingroup$ If you change the tech to read "a method of finishing iron to have an ultra-low coefficient of friction", many of the difficulties of working with such a material, and many of the science-based implausibilities go away. $\endgroup$
    – Lord Dust
    Sep 3, 2016 at 23:32
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    $\begingroup$ It would be so much better to have a frictionless shield. All attacks just slide right pass it... $\endgroup$
    – Skye
    Sep 4, 2016 at 7:12

4 Answers 4



with normal armor, you have pretty wide angle that still delivers full force. With your, enemy's weapon always slides. This has two benefits:

  • Less impact on your hero. 25 degrees in one way or another would still deliver 90% of force, give or take, so that's not that great.

  • Throwing enemy off-balance. That's your armor's greatest power. After one hit, when sword that's supposed to hit slides instead, enemy would lose his balance, and get confused. Both things makes him make mistakes, and allow your guy to win. Or at least give him chance to.


  • Hard to put on. Extremely hard, as you only can hold straps etc. Or you need some handles on the inside, and these can't be comfortable.

  • Poor quality. Because blacksmith can't really hold it in any way when working on it, mere fact it is recognizable armor shows he was master of his craft, at near miraculous level. But it would take a miracle to make it better than "crap" manufacturing quality.

  • It's iron. It has all iron's drawbacks when compared with steel.

  • Can't grapple. Pretty obvious.

  • Can't stop sliding. Not without risking his palms and soles.

I would rather have it sold to mages, and bought good set of full plate, and donate to temple to get me resurrected if it fails.

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    $\begingroup$ I really like the blacksmith argument. It almost makes me want to meet the blacksmith that made it and shake his hand. I'd probably find out that blacksmith was actually cursed by a witch to have ultra-high friction hands, and that's how he made the armor! $\endgroup$
    – Cort Ammon
    Sep 3, 2016 at 21:24
  • $\begingroup$ The last one isn't a drawback as only the outer surface is frictionless. This would probably help combat the first drawback as well. $\endgroup$ Sep 3, 2016 at 21:26
  • $\begingroup$ @CortAmmon I put them in order of priority... I imagine putting it on would be a comedy of "where did my armor slide this time?" and that's more complicated to explain / fix than one-time making it. $\endgroup$
    – Mołot
    Sep 3, 2016 at 21:27
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    $\begingroup$ Honestly,it's twisting my head figuring out how a frictionless solid would actually work. I wanted to comment on these benefits and drawbacks but after it twisting my head, I gave up. Though a good benefit is that blood should just slide right off without leaving a mark. $\endgroup$
    – Necessity
    Sep 4, 2016 at 0:48
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    $\begingroup$ The OP says that it is a "method of finishing an iron surface". So, on the miracle of creating the armor, I would say that the backsmith frist creates the armor as a regular one and then goes on treating selected surfaces to be frictionless.... which is still a miracle. $\endgroup$
    – Theraot
    Sep 4, 2016 at 7:07

I think he's going to be in for an interesting time if he ever falls or gets knocked over - frictionless armor means he's going to be sliding downhill at an increasing speed until he reches the lowest point, then up the other side slowing down, then back and repeat until he manages to slow himself down with the grippy bits. You may want to extend the grippy bits round a bit more - otherwise, if he gets onto his toes while trying to get up, whoops, frictionless again.

Interesting question as to whether it's going to be better or worse than normal armour for protection.

For bashing weapons, while they'll slide somewhat, you've still got the straight in component of the blow to worry about - so you're probably still going to get dents. And once you have a dent, any blows in that area are going to slide to the deepest bit - so instead of nearby blows being distributed as normal, they're going to get funnelled to the deepest bit and make it worse.

For cutting weapons (assuming they don't cut in) they're going to slide. Might be disconcerting for the attacker and could put them out of position, or slide to a joint in the armor - which might be bad.

Piercing weapons (like a pickaxe) might be a problem because of the sliding down a dent effect - once you have a dent, further blows slide to the same place, so that's probably worse than normal armour.

Getting the armour on and off may be a problem if it's frictionless on the inside of the armour as well - and I'm not sure how good a grip you'd get with only one side frictionless. While you can probably hammer holes into it for fixing straps (though you may need to build a jig to stop your tool and the armour sliding out of position), it may be fun putting things on / pulling things off if the strats re the only place you can get a grip.


European-style combat would need some changes. Plate armour with this low-friction surface would be of limited value. Full sets of steel plate were extremely difficult to breach; typically, in hand combat, an attacker would have two options. First, they could be conservative with committing their weapon, using footwork, finesse, and constant probing attacks until their opponent made a mistake and revealed a chink in their armour. Your low-friction finish wouldn't help much against this sort of thing, as the only significant attacks would be against unarmored spots or the weapon. Skilled opponents might not even notice.

Secondly, they could use the enormous mass of their weapon, aimed at spots from which their weapon could not deflect, to shove their armoured opponent around until a gap was revealed in their opponent's armour. Since this suit doesn't give your adventurer more coverage, and will only moderately affect mass weapons that aren't really intended to pierce plate armour anyways, your adventurer will only gain a moderate benefit by deflecting a certain small percentage of blows that might otherwise have bitten in and gone through the plate. Some opponents would be greatly surprised, but most would probably find the difference noticeable, but ineffective.

For this sort of combat, having your shield's surface be near-frictionless would be amazing. Many tactics used against "sword and board" opponents involve trying to shove the shield aside somehow, forcing them to commit large amounts of momentum to their weapon on questionable shots. But a skilled shield user often controls the angle of contact between weapon and shield, and most often the shield user's objective is deflection, not absorption. Deflected weapons in these circumstances will really drag the wielder off balance, and a full-bodied shield press will be almost impossible. For my money, just coat the shield, make yourself a medieval Captain America.

For point weapons like lances, pikes, longbow arrows and such, this sort of surface would also be extremely effective. Low-friction surfaces would deflect these almost effortlessly. Luck, as in finding the visor slit etc., would likely be the only way these weapons would do any damage.

All of this is predicated on steel plate. Using iron would present a number of issues that the low-friction surface would likely not mitigate. If you have not already, you should read up on iron vs steel for armour before committing to iron for your adventurer.


if it's say a frictionless foil cloth it is still unable to hold any pierce coz dent effect.When spike will be trapped in a dent frictionless will become ineffective.This goes for any other mat too. Second one is say hammer strikes when slide direction is in oppose to one in which it will be pushed by handle. All other shall be hold.

but if you wanna have to model any impact you have one force against another one on scene.And at begin of impact it's equal. something like that (friction power is vanishingly small at this moment,but it will grow very fast if you deal with common materials. Power will also have a flank component)


I guess you can think selfstate what that means in case of real frictionless surface. Answer is:there is no impact at all in this case. You'll have this picture frame by frame in different points till blade slides away completely There are also powers that're absent in this model,but it's insignificant.


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