Woodbutcher..I believe you are right, Seems like I have an old finishing book that says to make a tack rag you add a touch of varnish and turpentine. I have experienced the same effect with Watco, but no fire, just got hot. Thats why most have a metal container for finish rags, BTW...Maloof Oil, sold now by Rockler, is a combination of tung oil, urethane and boiled linseed oil. He lives near by, and in college we used to make our own Maloof Oil. Bottom line is you don't need to make a tack rag, I buy them for 70 cents. Keep an eye on those rags Butcher and dont get burned. Dave