I need to artificially stain a hat for a costume much like the ones you can buy these days with the fake dirt and sweat stains. I'm sure it is a combination of some sort of brushed on and sprayed on mixture - I just don't know what that is. I thought for sure by doing a search online I'd find some hollywood secrets but this is a subject that no one seems to have posted on before. I have a light colored almost gray felt hat that needs the fake-ness applied around the hat band area along with general dirt from handling. Any insight as to how the manufacturers do it?