Part 2 is here!
Take your ram and basecoat the teeth with Dheneb Stone.
The Battlewagon is then sprayed entirely with a gloss varnish and let to dry for a few hours. Next, grab your oil paints and some thinner. I use Daler-Rowney Black, Burnt Umber, and Raw Sienna for my weathering process. Create a 1:1 mix of Raw Sienna and Burnt Umber, and then thin it to a wash consistency using your paint thinner. Apply this wash over all of the model and let it dry for a few hours.
Once dry, create a 1:1 mix of Black and Burnt Umber and thin it to the same consistency as before, and repeat the process of applying the wash all over the model. Oil paints create a nice dirty finish that is excellent for mimicking grease, grime, dirt, and all the other stuff that would dirty up an Ork vehicle.
I only did these two coats, and already the model is starting to look great! Feel free to add more and more coats of oil paint, focusing on the areas where dirt and grime would accumulate. When you're satisfied, seal the model with a matte varnish. This will prep us for the next part - acrylic washes.
I will be using Games Workshop's Citadel washes from here on out, and having a matte seal on the model will allow my washes to settle properly on the model. Using Badab Black, apply a pin wash across all of the rivets on the model. Pin washing involves using just a little bit of wash on a small brush and dabbing just around small details. This will make the rivets pop a bit more.
Devlan Mud and Gryphonne Sepia are applied to the metal areas to create some extra rust and weathering. Skull White is streaked across the teeth on the ram.
Finally, paint in Chainmail to create exposed metal areas where the grey-brown is thickest. Wash the teeth with a 2:1:1 mix of water, Devlan Mud, and Gryphonne Sepia.