Weathering the 1/32 Merlins
I let everything dry overnight again and started the weathering process by dabbing a little Valleho Black Acrylic onto the engine block in random paterrns. This was set aside to dry. It's been warm and dry today so this took only a few minutes.
Next, I painted the entire engine with Ammo of Mig Neutral Gray wash. It can be applied liberally as most of it will be wiped off.
I waited a few minutes and wiped most of the wash off with a clean lint-free paper towel.
Once the neutral gray wash has dried (a few minutes), I aadded some dirty oil stains around leaky parts of the engine. This included valve covers, crankcase and some plumbing connections. I then added some separate pin washes of Mig Stone for Black and Deep Brown.
These "leaks" are really easy to poduce. I used some Ammo of Mig Fresh Engine Oil, Abteilung Engine Grease oil paint, black pastel chalk, Humbrol Smoke pigment and a couple of drops of mineral spirits. A fine brush is used to paint it on selected areas.