I didn’t have a technique either until 4 days ago…[:D] This is what I came up with.
- sprayed medium brown base of acrylic and let it dry REAL GOOD
- I drenched the base in turpentine to where it had puddles in some places. I then used burn umber, yellow ocher, white and black oils strait from the tube (ie no thinning) applied with a brush in randomly mixed shades to paint it. Staying farther to the burn umber shade. The puddled turpentine creates a thinner wash in some areas and thicker in others. you can also apply oil paints to the dry base then use a wet brush to bend an move the colors around. Go back an make some indidvidual stones odd shades. I also used some random green oils to simulate moss in the cracks. To finnish it up I used the same pastel wash I used on the tank on the base to give it visual continuity. It really helps marry the vehicle and base together…
Its a wordy explanation but I hope it helps… It really more of a trial an error. The worse that can happen is you’ll have to repaint it…