Right, I have used Teroson 9220 (an 80ml tube is just over £5 from RS Comps) and will be testing it around tea-time today! I cleaned off all the old black gunk (which to be fair could also have been Teroson although it was grey not black) degreased the surface of the arms (which had previously had the black paint removed) and then applied the Teroson. It went on easy, sticks well and doesn't run. I had plenty of time to create a partial sausage roll effect before it started to skin over (approx 6 mins). It takes 24 hours to completely cure so we'll see how well it works later......