I am thinking of using pigments to make gun powder residue and exhaust on an airplane. Has anyone done this?

What colours would be best? Would a black or a dark grey be best forthe gun ports?

What woulde good for the exhausts?

Ca

Hi Ca,

I have not used them but others have. I think it can be hit or miss. Th problem is that you'll have to seal them or they'll rub off. That can dull a NMF (Natural Metal Finish) if you build one.

Exhaust color? Depends. US WW2 gas had a lot of lead in it and many exhaust stains were more gray than black. German planes burned some gas that left very sooty black exhaust.

Black or gray for the guns? I use black, but it depends on what I am trying to convey. I think that the more shooting a plane did, the darker the residue would be. If the tempo of operations was fast, there would be little time for ground crew to wipe it down; if your plane is to be in a quiet zone, the stains would be less obvious.

Unfortunately, it seems to have become a trend to put streaks, from guns, right across the wing, and it simply didn't happen. Ammunition did not use black powder; watch any film of a test-firing, and the aircraft does not disappear in clouds of smoke. Then there's the groundcrew; riggers had a certain amount of pride in their charges, and, certainly in the RAF after 1942, were given strict instructions on keeping the front portion of the wing scrupulously clean. One ex-rigger told me how his pilot would lay a piece of cloth on the l/e, and, if it didn't slide off, was distinctly unimpressed. Underneath, where the empties fell out, was a different matter; there was a combination of oil, grease, and powder residue from them, but still not great swathes. I realise that someone will produce a photo which goes against what I've said, and I can find photos that back it up. Remember, too, that aircraft have regular servicing, and a Spitfire only flew for around 100 hours, before it had a major, which could include a full repaint.
Edgar

Use artist's chalk pastels instead. They're about a quarter of the price and the range is wider. The only slight downside is that you have to grind them yourself, but that's dead easy.

Colours: I'd never use straight black. A little dark brown will make residues look more authentic (subject to what others say about how likely residues are) and adds to exhaust staining too. Some exhaust stains are indeed grey, but that's often in the middle of the plume - the edges may be darker and shade from brown towards black. Check your references, I guess - which will also guide you as to where the airflow sends the plume.

One easy way to avoid problems with pastels / pigments coming off is to avoid touching them. If you really can't do that, hairpsray is a gentler fixer than varnish, and will darken the surface less. It will, of course, dull it too, but not as much. Some brands may react with some finishes, so you'll want to test it first.

Actually, Tamiya'a weathering set D has a color called Oil Stain. To me, this is a close approximation of the discoloring around, and on, the gun muzzles. It's hard to describe the actual color, but if you have ever looked at the end of the barrel of a gun (not down the barrel, but around the end) after it has had quite a few rounds fired through it you will see a sort of grayish/brownish residue. At certain angles it almost has an oil slick like appearance. In the high contrast black and white pics from WWII, this appears as a black, soot like staining that coats the muzzle brake and creates the appearance of black streaks and such. The build up of these deposits over the course of a day, after hundred, or thousands, of rounds of ammo kind of gives that impression, especially over light colors, but is not permanent and wipes off rather easily and would be quite often by the ground crew.

Now back to the weathering pigment, well they are more like make up cakes than pigment. While it will wipe off, you will not be able to blow it off...the stuff sticks well. As for applying it to models, well it would depend on how you are depicting the plane. After a "rough day at work", I would probably give it some heavy staining. But it depends on the guns. For guns that have no protruding barrels, I would put it around the opening in the wing but not streaking back over it or at least not really far back (a little over the front edge). Same with guns that stick out a little, like the guns in the cowling of Fw-190s. And if that cowling is painted a light color, this stuff will show up really well, but try not to over do it. If the guns stick out pretty far, like on some Spitfires, I would only put it on the muzzle. Like Edgar said, these guns use modern smokeless black powder and do not produce the big clouds of staining smoke. And while handguns will deposit black powder on your hands, that would be too small to put on a model and would be confined to inside the wings where the receivers are at. And at the end of the day, the ground crews would clean all of this up and wipe it off since, if left on, could cause a gun jam...and that would be bad.