How do you paint the burn marks from tanks exhausts?

[o3gan]

in all the pictures of space marine tanks the exhausts (i think theyre exhausts) have burns painted arround them. how do you paint this?

[njm3]

Could be a black drybrush followed by a lighter silver drybrush, a thin black wash, or stippling with black paint.

[SquigBait]

The way I do scorch marks on exhausts and gun muzzles on cannons and the like is a 2 step process. Paint up the pieces as normal for base (I tend to base the exhaust in rust, but yours may be 'stainless' type exhausts and you may wish to leave it silver) and start by drybrushinf starting from the tip working back a short ways with a dark brown. Let this dry and then take a flat black and again drybrushing from the tip work your way back a short ways, leaving just a bit of the brown showing. This yields a very nice soot/scorch effect with minimal effort.

[Hemal]

A mix of black and brown wash works well, as does painting the modell base scorched brown + black. Build up the layers gradually to where the metal wopuld be more scorched...

Another alternative is using the weathering powders..generally scorched metallic surfaces are such because of a build up of residue and weathering powers are a nice and realistic way of doing it

[winterdyne]

I do most scorching just with a black drybrush. On large items (drop pods, land raiders) I occasionally use carbon black oils too for streaking and control...

[ShinyRhino]

I paint my metal basecoat first. Then I do a light drybrush of bronze, then another light drybursh of a reddish brown, and finally another drybrush of flat black.. Leaves a nice heat patina on the surface.

 

http://i191.photobucket.com/albums/z43/goalie20/Warhammer%2040K/assaultsquad2.jpg

(Poor photo).

[Hemal]

You could even mix greens and purples in teh mix to give a really nice sheen which resembles the impact of heat on a lot of metal surfaces, or else some form of hydrocarbon residue refracting light...