Backstory: With the shirt finished, I needed to distress it. I wanted it to look worn, not new.
After the wash, I unstitched the edges of the shoulder patch and pulled threads from the remaining burlap to use to do a reinforcing stitch around the edges of the patch, inside the fraying. Then I used the thread I had previously used to attach it again, with big stitches.
When it came out, it was pretty dirty looking. I dried it, then rinsed it again, then dried it again. I did not use soap, because I don't have a washer and didn't feel like hand washing it, so I'm sure once it's washed it'll loose some more of the filth, but I think it'll still be enough to make the shirt look lived in rather than brand new fabric.
What I learned: I really enjoy distressing things; I think that's coming from the same part of me that loves wielding a chainsaw and the smell of motor oil and gasoline.
What I might try next time: Actually, motor oil might be good for distressing fabrics... I also want to look into natural dying more, the mordants you are supposed to use to help the fabric accept color (there are more effective mordants than vinegar and lemon juice, but that was what I had on hand).