Astartes armour corrosion.

[old git]

My school chemistry may be a little fuzzy but isn't rust only a corrosion of ferrous metals?

 

As far as I'm aware, marine armour is mostly a composite of adamantium and ceramite, supposedly two of the most incorruptible metals mankind has ever developed. Why then, when power armour is not composed of ferrous metals, do painters want to, for want of a better phrase, 'rust up' their marines? Especially when the maintenance of their armour is a priority for marines as far as is possible. Similarly, painting verdigris effects on bronze finished armour. The armour isn't bronze, it's just a finish.

[PeteySödes]

Warpy oxidization?

 

I think rule of cool is just in effect really. Certain things your eye expects to see with certain weathering techniques. I get your callout but I'd never give anyone grief for it personally.

[armarnis]

i mean, terminators wear STONE crosses worked into their armor on the shoulders (and everyone else bearing a crux does so too), its reasonable to assume the artificers did not only use a spraycan to spray some fancy finish onto the armour but weaved a layer of true bronze into the armour without undermining its protective capabiilities!

 

on the normal marines, afaik there is no adamantium in their armour involed, mainly (!) ceramite which is some tec hocus pocus alloy of various metals and mostly ceramics. as its described as steely grey and/or silvery in various accounts, i think its a fair assumption that it MIGHT have some metals in it that might corrode and rust. and yeah, armour maintenance is something they do for sure if they have the time for it! marines can run, climb, fight and do some crunches for DAYS without end! so i always think once they embark their strike cruiser each makes a mental note: "once i am home in the monastery, first thing is i go into the power armor wash station!" but 5 minutes after they that they are called to some lousy dirthole far far away :D rule of cool, an marine in all his majestic glory looks so much cooler if he is battered and bruised but FIGHTS ON!

[Evil Eye]

With decorative elements like bronze, brass and copper, it is possible that the metal is actually "the real deal" as authentic metals such as bronze would be considered rare and valuable, especially if the artifact was Terran in origin.

 

With the actual armour itself, it's worth bearing in mind that in the 40K universe, even putting aside the inherent rubber physics/"rule of cool", there is far more at play than present-day known laws of science.

In the case of stuff like, say, Tyranid bio-weapons, the acids and solvents employed by the Hive Fleets in their living munitions will have been specifically formulated and evolved to attack adamantium and ceramite, and may contain more than mere acids, or alkaline compounds for that matter; abrasive particles, electrochemical elements producing electrolysis and even micro-organisms that quite literally eat through armour (like the oft-forgotten Tyranid phage cells) are all likely candidates for causing corrosion or chemical breakdown of Astartes armour. Whether or not this would manifest as ferrous rust is another matter, but it looks cool.

 

And then there's the powers of Chaos and the Warp, which due to being metaphysical and thus not constrained by the rules of science, can basically do whatever they want. The aura of decay possessed by Nurgle's servants may manifest as rust not through a conventional chemical reaction, but simply because rust is a symbol of ruin, neglect and corrosion, and thus ceramite and adamantium infected by Nurgle's touch would appear to be rusty due to being metaphysically, spiritually tainted. This applies to both metal of loyalists whose armour is weakened by the curse of the Lord of Decay's ire, and those whose battleplate is blessed with nigh-invulnerability from his gangrenous touch- whilst the effects are very different physically, the cause is the same; warp-spawned contamination.

So TLDR: Whilst under conventional circumstances you'd be right, 40K's environments and metaphysics are not conventional by any means, and there is nothing stopping Astartes armour materials from "rusting" (even if it isn't actually rust). Rule of cool takes precedence due to literally being part of 40K's laws of existence.

 

THAT SAID

 

There's room to play with all sorts of effects for exotic corrosion and degradation on materials when modelling and painting. For example the gold on my Emperor's Children is shaded with Druchii Violet. Whilst the IRL reason is because it looks cool and adds visual interest (and contrasts with the gold itself well), in-universe the purple tone is actually a patina collecting in the recesses of the armour- such is the spiritual corruption of the traitors, their wargear and the environments they dwell in that even the normally stainless gold is tarnished with the gaudy violet of excess and sin.

[Irbis]

With decorative elements like bronze, brass and copper, it is possible that the metal is actually "the real deal" as authentic metals such as bronze would be considered rare and valuable, especially if the artifact was Terran in origin.

 

*cough* bronze/brass are technically not a metal *cough*

 

Also I always thought gilding on SM armour is either just paint, or at best a tiny layer of shiny metal as most of decorative stuff is so soft and heavy it would impair you. If you tried to make armor out of gold, enemy wouldn't need rending claws to pierce it, a normal knife would suffice. I like GW finally noticed that too and Custodes now actually use 'auramite', whatever that is, not gold to make their battle plate...

[RolandTHTG]

 

With decorative elements like bronze, brass and copper, it is possible that the metal is actually "the real deal" as authentic metals such as bronze would be considered rare and valuable, especially if the artifact was Terran in origin.

 

*cough* bronze/brass are technically not a metal *cough*

 

Also I always thought gilding on SM armour is either just paint, or at best a tiny layer of shiny metal as most of decorative stuff is so soft and heavy it would impair you. If you tried to make armor out of gold, enemy wouldn't need rending claws to pierce it, a normal knife would suffice. I like GW finally noticed that too and Custodes now actually use 'auramite', whatever that is, not gold to make their battle plate...

 

Being as the latin name for gold is Aurum, I'm betting it's supposed to be an allow of Gold and Ceramite somehow. 

[Arkhanist]

My school chemistry may be a little fuzzy but isn't rust only a corrosion of ferrous metals?

 

 

My last chemistry studies were quite a lot of years ago, so forgive me if I get any details wrong; but this is what I remember.

 

Oxygen is quite a reactive gas, so it oxidises a lot of things - if there was an alien life form that evolved in a different way, they might view an oxygen atmosphere like we would view a chlorine gas one. Other electron acceptors also oxidise things, some more aggressively than oxygen.

 

So yes, 'rust' is oxidation of ferrous metals with that characteristic hue - a lot of iron oxide is why mars is red, for example - but it's only only type of oxidation. One difference is that many oxides then provide a sufficient barrier that further oxidation doesn't extend beyond the surface. When you polish dull aluminium, you're removing the aluminium oxide layer; it then dulls over time as a new one builds up, but it doesn't oxidise all the way through. Iron oxide (rust) has holes, so rust can continue to extend deeper into the metal, with water as a necessary catalyst ('ordinary' formation of rust goes through a few stages which require water)

 

IIRC power armour has a ceramite ablative layer which is ceramic-like for heat/energy dissipation and some kinetic protection. Then plasteel and adamantine plates for the main strength all of which one would imagine don't rust in the iron-water-rust sense. However, with the weird and wonderful chemical and organic nasties out there such as alien atmospheres, as well as weapons from dark eldar, nurgle, tyranids etc it's certainly possible that there'd be something that reacts destructively with them and _looks_ orange/red/brown like rust.

 

Relatedly, alloy trims like bronze could well actually be bronze - it is decorative, after all, like the paint on the ceramite, and these guys hang actual parchment blessings and feathers and bones on their armour so it's certainly feasible. Patina would be part of the appearance!

 

Personally, I don't rust normal space marines for the maintenance reason - as you say, they're going to try and maintain their battleplate. Battle damage, oil, scratches etc, that I do do to represent them being in a campaign so they haven't had time to clean, repair and repaint it. Plague marines on the other hand, they just demand to be rusted and gooped up, if there's anything that can corrode power armour it's a plague marine's secretions, and nurglings playing on them, and whatever other horrors Papa Nurgle can come up with, so a few holes to let their warp-mutated flesh spill out is probably more comfortable!

 

Squigsquasher's idea of it being metaphysical warp-spawned corruption is also really cool though.

[Brother-Chaplain Kage]

Yeah, rusted ceramic-alloy space magic armor shouldn't rust, but it's become such a thing now with all the streaking washes and weathering paints/powders that it's never going away. It's just as dumb as dumb as a bolt rounds supposedly being caseless, yet they still have ejection ports. And even dumber still, those ejection ports rarely line up with the barrel. 

 

When I was still working on my Crimson Sons, I imagined they were in an environment that was toxic enough that it was eating away at the paint on their armor and the acidic rain was leaving streaks of dissolved paint, but it wasn't strong enough to actually hurt the armor itself so none of it was the red tones of rust. The result being their dark blue armor was various lighter shades of blue with heavy weathering.