Iron objects in which little or no metal remains may be stabilized by soaking out all soluble chlorides in changes of hot, but not boiling, distilled water or weak alkali while supported in a close fitting base of plaster of Paris impregnated with Cosmolloid 80H (a micro-crystalline wax). The method of making the base by pressing the object gently onto a thin latex rubber sheet laid over wet plaster of Paris is also described. Alternatively the unstabilized object may be impregnated directly while placed in its base, reliance being placed upon the impermeability to moisture of the microcrystalline wax used as an impregnant.