Originally Posted by dizzymonochrome
Melt and then brush on candle wax. I went to a film costuming exhibit once and they had a video playing next to the display for a movie that was supposed to be set in Alaska, showing the costume designers using different consistencies of melted wax, brushed and dripped onto the actor's parka. They used varied coarseness and widths of brush bristles to get a realistic look. A few strategically placed drips looked like the jacket had been wet and then it was so cold that it instantly froze.
Wow sorry, I just gotta say, this is a really cool idea.
Also if you have the time/patience/skill, a combination of that and hand embroidery for the details on the shoulders would be really sweet. I think I may have seen some fabric that kind of had that look of his pants at joanns or something too though? Don't quote me on that though, I have a weird memory.