What Is Pewter? Composition and Safety


What Is Pewter?
Pewter is a tin alloy. Older pewter contains lead, but the modern alloy uses antimony instead.
Pewter cream pitcher, circa 1780, showing characteristic color (Missouri History Museum)

Pewter is a tin alloy. According to ASTM standards, it contains at least 90% tin. Modern pewter also contains antimony (5-10%), copper (2% or less), and sometimes bismuth and silver. Old pewter contains tin, alloyed with lead and copper. Antimony, copper, and lead make pewter harder than pure tin and give the metal a blue tint. Polished pewter is a blue-silver metal, resembling platinum. However, pewter rapidly oxidizes to a gray patina (antimony pewter) or nearly black patina (lead pewter). People have used pewter to make practical and decorative items since the Bronze Age (c. 1450 BC).

Is Pewter Safe to Use With Food?

Pewter that contains lead is not safe for use with food. Acidic foods and beverages, such as wine, fruit juice, tomatoes, and salad dressings, leach lead vigorously from the alloy. But, even neutral substances, like water, absorb lead from the metal. Jewelry made from pewter that contains lead also poses a health risk, as some lead may be absorbed through skin. Children who wear jewelry may place it in their mouths. Pewter items that contain lead may be displayed as decorative items, but shouldn’t be handled or used.

Lead-free pewter is safe for use with food and for jewelry. Elemental antimony (as in an alloy) does not pose a health risk, but is unclear whether the metalloid absorbs across skin. Antimony compounds are toxic, so it’s best to use polished pewter in contact with food, avoiding any oxidation products. The metal isn’t the best choice for long-term food or beverage storage. Pewter is unsuitable for cookware because it has a relatively low melting point [170–230 °C (338–446 °F)]. Do not use pewter in the oven or microwave.

How to Test Pewter for Lead

Two quick ways to check for lead are to look at the color of the metal patina (very dark oxidation usually indicates lead) or examine the mark left from rubbing the pewter item on a sheet of paper (heavy and dark mark indicates lead). Another method involves dipping the item into vinegar and checking for a white stain, theoretically indicating lead acetate or lead carbonate. However, these “tests” aren’t reliable.

The best way to test for lead in pewter is using a lead test kit from the hardware store. This involves swabbing an area of metal with test chemicals and looking for a color change. For most kits, pink or red indicate lead. After testing, rinse the pewter item with soap and water. The Canadian Conservation Institute uses Plumbtesmo 90602 test spots, but warns tellurium, cadmium, silver, and strontium can interfere with the test. In other words, if any of these elements occur in the pewter, it can test positive for lead even if the alloy doesn’t contain it.

How to Clean Pewter

The natural darkening over time adds beauty and character to a piece. Polishing old pewter typically decreases its value. However, if pewter becomes soiled (or you just like it shiny), simply wash it with warm, soap water and dry it with a soft cloth. Avoid using abrasives, as the metal is soft and easily scratched. Do not wash pewter in the dishwasher.

Is Pewter Magnetic?

Pewter is not magnetic. None of the elements found in the alloy are magnetic, regardless of whether or not pewter contains lead. Magnetism may be used to distinguish pewter from iron-based alloys, but not from gold, silver, sterling silver, or platinum (all non-magnetic).

Pewter vs Mexican Pewter

“Mexican pewter” is not actually pewter because it does not contain tin. It is an aluminum alloy, typically made by recycling aluminum cans. It is used to make decorative items and tableware that resemble pewter.

References

  • Agency for Toxic Substances and Disease Registry (October 2019). Toxicological Profile for Antimony and Compounds.
  • Campbell, Gordon (2006). The Grove Encyclopedia of Decorative Arts (illustrated ed.). Oxford University Press. ISBN 978-0-19-518948-3.
  • Hull, Charles (1992). Pewter. Osprey Publishing. ISBN 978-0-7478-0152-8.
  • Shotyk, W.; Krachler, M.; Chen, B. (2006). “Contamination of Canadian and European bottled waters with antimony from PET containers”. Journal of Environmental Monitoring 8, 288-292. doi:10.1039/B517844B

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