11th August 2013: Weathering Shirts Picked up 'burnt umber' and 'sap green' acrylic paint which mixed to make a great murky dirt brown.
After a bit of trial and error I got the best effect by painting it on normally, working it into the nooks of seams and top stitching, then going over it with coarse sandpaper (like dry-brushing for fabric). This tattered up the surface and left the paint looking properly worn into the fabric.
Extra sandpapering on points of wear (hems, pockets, fastenings, knees/elbows etc) made it look even older. The photo is a comparison shot when I'd only done the right hand side.
Finally I added some random mud wipe marks and sandpapered those down to look like old grime.