I have a Marx 6" lumber car that I just had cleaned and wanted to add a repro load. I felt the fresh lumber looked a little out of place on a unrestored 74 year old car. Asked for a few opinions and ended up combining two ideas. First, the pieces were soaked in plain old Lipton Tea for a while. This took a away the fresh new wood color a bit. After drying, I rubbed them with fresh dirt lightly. I like the look. Not old and dirty, but not fresh cut white wood. The first photo is the completed car, the next photo has a fresh piece of lumber sitting on top. Pretty much the subtle older look I wanted.
Steve