There are different types of paint pens, some water-based and some oil-based enamel. Only use the oil-based enamel ones (the Decocolor ones I use are this type), as those are truly permanent. Surface prep is also important, so remove all traces of grease first using denatured alcohol. Keep a rag moistened with mineral spirits as you apply the paint-- if you mess up, the mineral spirits will remove it instantly. And the BEST way to make the outlining permanent is to clearcoat the entire frame afterward.