The analysis of Roman metal objects revealed that there were iron objects completely covered with bronze. The greenish spots found on Roman iron bells were not solder but the remaining parts of a complete copper alloy covering. The same is true for the Hallstatt and La Tène Period. Also bells, keys, locks, and strigils from the Roman period were found to be covered with copper alloys. Experiments showed that such a coating is obtained when the iron object is covered by a mixture of bronze or brass fillings, beeswax, and a flux like borax or sodium chloride, mantled with clay, and heated up to 900-1100°C.