Just something I've been discussing with my GM. Obviously Dark Heresy will sometimes provide scenarios in which you have to go lite on the gear. Situations where walking in with a rocket launcher strapped to your back, and a Power Axe on your belt will give the wrong impression. So concealed weapons can sometimes be a boon. Fortunately, there's some rules on concealing weapons-- notably the Compact rule for guns, and something like a knife could be hid easily enough. Hell, in the right social situation a sword may even not be unexpected wear, anyways.

But armor seems to be a whole different ballgame, and I was wondering on whether or not it's feasible to hide any kind of armor type underneath your clothing. I was hoping that this could be done with Mesh armor, but my GM's been a little disparaging of this, suggesting that Mesh armor would still be noticeable if you hid it under your clothing-- ie. You could do it, but it wouldn't be too hard for an observing eye to notice you're wearing armor underneath your shirt.

Are there any armors that are any better for these sorts of situations, or that might be "socially acceptable wear" as it were?

In the core rulebook, I haven't found anything like that. However, I would houserule that you could get a set of armour that is the equivalent of gang leathers, but adapted to more formal occasions.

Perhaps you could discuss with your DM the use of Xeno Mesh as an alternative.

Hardened Bodyglove, Inquisitor Handbook.

A light bodyglove with plates over vital points to protect the organs that can be worn under tailored clothing.

Our houserule is that dress armour has its Cost doubled and its Armour Piercing Protection halved, rounding up. Dress armour is, of course, quite obvious.

Actually concealed armour are stuff like reinforced bodygloves.

The typical mid-hiver will probably try to avoid people with swords, pistols and flak, and it makes PCs stand out just as much as the same sort of gear makes Enforcers stand out. But it is stuff you can get away with in public, without causing a fuss. Basic Weapons & Carapace, not so much.

Xeno-mesh is kinda like a wet-suit. It's thick and bulky enough to be noticed under a regular, modern day suit, but could go concealed beneath fancy robes or military greatcoats. It's not comfy, though, and you would be kinda stiff and hot walking around in it all day.

A Good or Best Hardened Bodyglove might work, but it's still armour-plating. Meaning, it would "stick out" under a modern, tight-fit shirt.

Well, we always handled it with Mesh-Armour being concealable (better craftsmanship = better results of course) and most Best-Craftsmanship Armors also working as dress-uniforms (for example for the Guardsman) while still obviously being armor. But, yeah, any kind of bodyglove would be easily concealable as well.

We tend to work it on weight; so (for example) best-craftsmanship flak probably looks like a tailored thick coat.

Essentially, I usually allow any non-plate armour (plate, carapace, powered), unless you can give a good reason for wearing it (such as guard "dress uniform", as noted).

We used weights as a "place to start" as it were, and I might go along with best quality mesh being concealable.

Maybe. It still weighs 1 Kg (reduced by half from 2 Kg).

Normal clothing weighs about 1Kg in total (it varies a bit, of course, a business suit might weigh 1-2).

By comparison, a regular wet-suit weighs in at anywhere from 1-4Kg depending on thickness. (The skin-tight, thin 3mm ones weigh less)

Point is, clothing weighs bloody little! And even the best armours weigh quite a bit in comparison.

Putting on Best Quality Mesh, it is still going to weigh the same as your regular clothes.

It might be concealable, it might not, but a regular xeno-mesh cowl (or gloves) weigh 0,5Kg, as much as a heavy pair of jeans. Now, wrap your jeans around your neck and see if that's easily concealable

Ok, the last point wasn't really serious Armour has higher density than clothes, and will thus have lower bulk. But don't be fooled into thinking that a mesh-cowl is light. 500g on your head is quite a lot. A decent bike helmet weighs in at 260g, and isn't remotely concealable.

TL;DR: If you go by weights, almost nothing from the book is concealable.

Flak and mesh are both emminently concealable, they are fibrous flexible materials that could theoretically be used to make any item of clothing. Of course an armoured garent would compromise on protection for subtlety and utility but he extent of this trade off is variable depending on quality and materials.

The obvious example is a flak greatcoat. It`s not a hulking puffer jacket like a guard grunts flak gear it`s a heavy coat impregnated with flak weave in it`s lining.

I allow clothing with a mesh membrane sowed into it, giving it AP3 with all the looks of normal clothing, I mean there's already bulletproof jackets made to resist a 44 magnum round at point blank (talking few inches here) so in the far flung future, pretty sure the Inquisition would have found a way to get a mesh membrane into everyday clothing.

Hey- even Shadowrun does it, and that's only 40-50 years away...

I group Dark Heresy armor into three rough classes based on how easily they can be concealed:

1. Combat armor includes Guard flak, carapace, and power armor, and anything else incorporating a helmet. It is clearly military-grade gear, and wearing it signifies that the user is prepared for a fight. This armor is not concealable in the slightest and will draw unwanted attention to the user anywhere besides a war zone.
2. Subtle armor includes flak vests*, jackets, cloaks and greatcoats. This does not attract the same attention as military armor but can be noticed by astute observers, and if the character is searched the armor plates and flakweave cloth will certainly be discovered. Generally these armors are not concealable, but neither are they immediately recognizable as armor. This is certainly up for interpretation, but I'm basing my decision on the Edge of Darkness adventure. In the introductory scene, Interrogator Sand wears a flak jacket in the form of a heavy white coat; the Acolytes must pass an Awareness test to notice that the jacket is armored.
3. Concealable armor includes armored body gloves and mesh armor, and it can be worn in public without anyone realizing the character is protected. Body gloves can be worn under other clothing, and mesh armor can be designed to look like ordinary clothing. Only careful searching can discover this armor, making it ideal for undercover work. My interpretation of mesh armor is that it looks like fine clothing or a form-fitting body glove but hardens when struck by an attack. The Black Crusade source book has a picture of an Inquisitor dressed in what appears to be a broad-brimmed hat and long coat, and her stat block confirms that this is in fact mesh armor that covers ALL hit locations.

* = Flak vests (similar to modern Kevlar vests) are easily recognizable as armor but can be worn under heavy clothing, making them much more concealable than military armor, but isn't quite as stealthy as mesh or body gloves.

Not included in these categories are clothes that are not explicitly designed as armor but still have protective value. This includes quilted vests, heavy leathers, beast furs, and even xeno hides. Because these are not actually armor, these don't arouse suspicion unless worn in socially inappropriate settings. Imagine walking through Gunmetal City wearing a mantle of fine snow leopard furs...

Bodygloves, Mesh and Flak should all be concealable in various ways, depending on the particular form. Body gloves would be the easist, seeing as they are skin-tight and can fit under other clothes. Mesh is lightweight, flexible, and can easily be made hidden in a layer in clothing somewhere. I would rate the "basic" mesh armour as identifiable (it would look like little squares or hexagons in a chainmail like flexible layer in my mind), but spend money for specially tailored stuff and I could certainly say you could have it tailored into a form of clothing which would pass any visual inspection, and anyone making a cursory physical examination (a pat down for example). However, under closer examination, such as someone deliberately feeling the material, and it would probably could be identified by someone who knew what it was.

Flak is made into clothing (usually military), therefore it is entirely concealable. However it would have to be trying to replicate heavy duty clothing, as otherwise the nature of the material would not match the style it is meant to represent. Outdoor coats and the like, yes; a dress shirt, no. Anyone with any experience could tell it was flak with a physical examination, unless the item in question was bulky enough that the material could be made into a layer within the clothing, rather than just being the material itself.

All the flexible armours could also be concealed by other clothing items, of course, but there are practical issues to think about. A flak vest under a coat would pass visual inspection, but anyone patting you down would probably notice it, and it is going to get darn warm. Mesh can probably be worn under most outer items, but unless specially tailored would likely be noticed on a patdown as well. Guard flak armour? The uniform itself (which is the armour) is quite bulky, which just couldn't be hidden under clothing without being very obvious, and then there are the additional hard plates etc which just cannot be hidden.

Carapace and power armour are obviously a big no-no (ok, maybe a carapace breastplate could be hidden under large coat)... though way back in 1st edition 40k you used to get "skintight" power armour

You could go for small pieces of armour designed to protect vital organs. For example a carapace disc over the heart or a hardended collar.

Rules might be something like

Heart plate: AP6. The Heart plate has a 25% chance of offering protection to hits to the body.

Hardened Collar AP5 The Hardened collar has a 15% chance of offering protection to hits to the head.

etc.

There is also the different matter where it might be perfectly acceptable, or even fashionable, to wear certain types of armour in social circles. During certain periods of the medieval era brigandine armour (small overlapping metal plates affixed to the inside of a cloth covering, usually with distinctive patterns of metal studs showing on the outside) was apparently so fashionable clothes were made that looked like the armour, even though they didn't actually provide any protection. Mesh tends to suggest you have the wealth to aquire it, and flak (in a more tailored style) might be all the rage in a period when everyone is wanting to show their martial patriotism (say a new Crusade has been announced).

You could go for small pieces of armour designed to protect vital organs. For example a carapace disc over the heart or a hardended collar.

Rules might be something like

Heart plate: AP6. The Heart plate has a 25% chance of offering protection to hits to the body.

Hardened Collar AP5 The Hardened collar has a 15% chance of offering protection to hits to the head.

etc.

Although I like the creativity of the idea, I'm not sure it would be a good adition to the game. Yet another mechanism before you can establish damage won't help to speed up combat.

You could go for small pieces of armour designed to protect vital organs. For example a carapace disc over the heart or a hardended collar.

Rules might be something like

Heart plate: AP6. The Heart plate has a 25% chance of offering protection to hits to the body.

Hardened Collar AP5 The Hardened collar has a 15% chance of offering protection to hits to the head.

etc.

Although I like the creativity of the idea, I'm not sure it would be a good adition to the game. Yet another mechanism before you can establish damage won't help to speed up combat.

Yeah, as a general piece of equipment probably isn't the most efficient. But I am guessing the situations which require you to go without armour are scenarios involving limited, quick violent encounters.

For example suddenly getting shot at by a sniper, or stabbed by an assassin rather than full blown cultist ambush. In the latter cases I would imagine unarmoured PCs will be trying to run rather than fight.

You could go for small pieces of armour designed to protect vital organs. For example a carapace disc over the heart or a hardended collar.

Rules might be something like

Heart plate: AP6. The Heart plate has a 25% chance of offering protection to hits to the body.

Hardened Collar AP5 The Hardened collar has a 15% chance of offering protection to hits to the head.

etc.

Although I like the creativity of the idea, I'm not sure it would be a good adition to the game. Yet another mechanism before you can establish damage won't help to speed up combat.

Yeah, as a general piece of equipment probably isn't the most efficient. But I am guessing the situations which require you to go without armour are scenarios involving limited, quick violent encounters.

For example suddenly getting shot at by a sniper, or stabbed by an assassin rather than full blown cultist ambush. In the latter cases I would imagine unarmoured PCs will be trying to run rather than fight.

In the group that I run it is a rare occurrence to see them run away (once or twice in 2 years of playing once a week!!) or to get them to ware something that is appropriate to the situation they are in. Which often causes much hilarity.

My group tends to wear flak robes or armored bodygloves most of the time. If they go around in more obvious armor, they have an unfortunate tendency to be attacked by snipers or gangs of hitmen They break out the Guard flak and carapace when it's time to kick down doors and purge heretics, since they're expecting a fight anyway.