How do I recreate the white exhaust staining on a Lancaster bomber ?

[ShinyIIACRIC]

Good afternoon everyone,

I'm currently putting the finishing touches to a Tamiya 1/48th scale Lancaster and would like to know how to recreate the White exhaust staining on the upper wings?

Any advice would be greatly appreciated

Many thanks

Graham

[JasonC]

Airbrush - Try a heavily thinned light grey paint - go slow!
Brush - You could apply either light grey or white weathering pigments or ground up artists pastel chalks (a.k.a. 'hard' pastels)

cheers,
Jason