It's quite easy really, Might be worth trying one first though, Go and buy a can of Mr Muscle oven cleaner and put them in a bowl or tin...Not too big just enough to fit them with a little space and completely cover them in it, Leave them for 20 mins and take one out... if they are turning black give them a quick rub over with a Brillo pad and the coating should start to come off easily, If not just spray the rest of the can on them and leave it a bit longer....It can get a bit tedious cleaning them all but worth the effort I think...If you want to polish them up a bit after, get a 12mm threaded bar or cut the top of a bolt and put it into the nut and the other end into a cordless drill, Get some metal polish on a rag and spin away...Good luck, Gaz

 

Great, thank you.