Shellac is a hard impermeable coating that can be applied to artifacts that are heat sensitive. Shellac can be removed with alcohol or buffed with steel wool to decrease its glossiness. Microwax for those artifacts that are not heat sensitive offers the added advantage that it supports and helps consolidate brittle or flaking pieces. Microwax can, however, give the object a yellowish hue. For this reason wax cannot be recommended for aluminum or bright silver.
Gold is a very ductile rare heavy metal.
Found as plating on ornaments or in solid form in coins, and as bullion it is relatively unaffected by immersion in water. Little concretion can form on gold and little or no corrosion product tarnishes its bright color. Occasionally gold can be partially concreted or covered with corrosion products if it is submerged in close proximity to other less noble metals such as iron. An acid soak should not be used if gold plating covers a less noble base metal than brass or nickel. If this is the case a careful swabbing of the artifact with a citric acid soaked Q-tip is the best way to clean the plating.