Spontaneous combustion is a serious problem with almost any oil soaked cloth . I once saw a guy open up his new linseed oil soaked canvas sheet to show every one , the thing gave off a puff of smoke and burst into flames as the air ,oxygen , got to it . I have seen oil soaked rags thrown in a drum, almost burn down a workshop and a cloth used to mop up some mutton fat from a barbeque get so hot it melted the plastic bucket it had been placed in . My advice is dont make one , and if you do keep it stored unrolled and out of the house or garage .