This product is constructed with cast Pewter, an alloy made from tin (Sn 92%), antimony (Sb7.5%), and copper (Cu.5%). Pewter has a relatively low melting temperature between 420F-500F and is not suitable for heating with a direct flame or within an oven. Pewter is nonreactive and food safe. Even though it is nonreactive if salt is stored in the jar and you live in a humid climate, the salt can accelerate the natural oxidation or darkening of the interior. The exterior has been oxidized or artificially darkened and rubbed back to accentuate the surface texture. The exterior is sealed with a buffed beeswax finish. The interior is the raw metal with a brushed surface. This container should be hand washed only with a mild detergent, rinsed with water and hand dried. Over time the material may need additional maintenance. If the pewter develops unwanted dark splotches or a dull greyish haze, clean it with soapy 0000 steel wool, rinse and dry. The wax surface will usually only require mild buffing with a terry cloth rag to refresh the satin luster. If the wax finish must be repaired apply any beeswax based cutting board or salad bowl finish and buff the finish once it has dried.