I'm assuming you're using Halfords or Holts rattle cans or similar? You'll need to get all the wax off it before you clear it. Now, I never had to do it but hot water and Fairy liquid and an old toothbrush should shift it I'd imagine. I'd spoon test everything you've already done, try to get it off and see how you get on. Maybe Geoff knows, if he's looking in.