I like this for cleaning alum not to harsh. I mixed up some in a gal bucket and dropped a spool of alum mig wire that was real old in it for a couple of minutes rinsed it of blew it out and let it dry welded like it was brand new I don't know why it wouldn't clean your filler rod a gal will last you a long time and it beats wire brushing or sanding. I buy it at a local cleaning supply.