Pink emulsion, over white, over original radiator finish. Chipped and splashed with all sorts of muck over the years. Buy a new one? No - just dismount the rad., lie it across trestles, cover it with an oblong of sheet, splash on meths. liberally, cover with plastic sheet, wait 10 mins, wipe clean by progressively rolling back sheet and wiping off emulsion gunge with wet cloth (lots of rinsing).
It looks almost new!
J.B.