for regular tung oil application, i tend to use sandpaper to apply it.  I get the bow all slicked up and ready to go, then cover it in tung oil.  Then while it's still wet i hit it with sandpaper.  After doing the entire bow, i rub off all the sludge with a rag.  Then i do it again, with a higher grit, continuing up til i'm using wet/dry sandpaper of at least 320 or 400 grit.  It's messy, but it makes for a very nice finish.  Then, tru oil.