It does not address the serious problems of preserving archaeological metals excavated from land or marine sites. People who collect unconserved archaeological artifacts should be aware that those types of objects are rarely stable if left untreated. Galvanized or tin-plated sheet is also a familiar material in historical collections. Ferrous metals are magnetic so the presence of iron can, therefore, be easily identified with the use of a magnet. By far the most widely seen problem associated with metal artifacts is corrosion.
Active corrosion causes a continuous loss of metal from the object.
Mishandling, however, can result in breakage, bending or cracking. Cast iron is usually a relatively brittle material and will not bend as one might expect metals to do. Salts, oils and moisture can lead to metal corrosion, so if you handle metal artifacts with bare hands you risk damaging them. Stable surfaces may appear blue-black to brown, and are not scaling, flaking or pitting. This kind of compact rust that does not progress may actually protect the object if it is left intact.