I'm assuming that you have an open face wheel an that the drum is exposed...inside covers plastic or metal will hold heat in..the fins on the drum for a purpose, to cool the braking system...an over heated brake drum or rotor will have a tendency to warp and cause a vibration when braking...painting is OK but if you want to do it right, either purchase new drums or have your old ones sandblasted on the outside and power coated, the colors are endless and it will not rust off and very hard to chip