How metal textures inFallout4 work (diffuse, specular and palette)

Im not a native english speaker, so please excuse a few grammar mistakes.
Also this is my first tutorial, so be nice to me :D

1.       The 10mm Pistol has different kind of maps. The diffuse, specular and normal map.
And there is also a very special one -> thepalette.dds. Im not going to cover the normal maps here.



2.       First off all I want to take a look at the specular map  xxx_s.dds
Im still not 100% sure how this map works but I will tell you what i know until now.


The specular map has 3 Channels: Red , Green and Blue



The blue Channel has no effect.
 
The red and green channels define how shiny and how bright the texture is.
If I change the red and green channel to 100% white I will get a chrome texture


If I turn red and green to 100% black I get a dark and matt texture

The combination of light and dark areas in the original xxx_s.dds is giving the texture the metal look, it defines the shiny
and not shiny parts. Its not the diffuse map that is doing any of this.
 
Like I said Im not 100% sure what the green and red channel are doing on their own.

I suggest you to use TrophiHunters Photoshop Actions for normal maps to convert the xxx_s.dds and to save it as 3dc format with your
nvidia dds tools in photoshop if you are playing around with the specular maps.
Saving it in DXT5 often leads to strange results except you want to have the
full chrome or the full dark and matt look.
 
http://www.nexusmods.com/fallout4/mods/1045/? 

3.       Now I want to show you a really interesting map. The palette.dds



This map is maybe the most important one for retexturing your weapons with a lot of metal (like the 10mm pistol)

Lets see what it does.

You may see 2 areas in this map



Im going to change the colors of them like this


And lets see what happens.


All the metal parts of the weapon turn red. And again its not the diffuse map that is doing this.
The darker red parts (like on the scope, the silencerand the hammer) are less shiny (darker) parts of the specular map.

But where is the green color?

Now this is the part where the diffuse map becomes important.

As you can see, the map is really bright. I think all the grey parts are brighter than
RGB 128,128,128 (thats the middle between white and black) and i think that is the border between the red and green area on the
palette map.

If we turn this map darker…


Our little pistol turns into this.

Only the bright parts of the diffuse map are now red,the rest turned green. (the effect is not on the whole weapon, because i only
edited the 10mmPistol02_x.dds and they dont contain the the whole weapon)

Some of you may tried to make this weapon darker or black and only edited the diffuse map.
You will get a really rusty gun if you do that and I hope now you know why.


You should have made your palette.dds and maybe your specular.dds a little darker instead.