How to Clean and Preserve Metal Artifacts Found in the Field

Cleaning and preserving metal artifacts is a crucial process for archaeologists, historians, and hobbyists who engage in fieldwork. These processes not only enhance the appearance of the artifacts but also ensure their longevity for future study and appreciation. Proper treatment can prevent deterioration due to environmental factors, corrosion, and dirt accumulation. This article aims to provide a comprehensive guide on how to clean and preserve metal artifacts found in the field while employing scientifically sound methods.

Understanding Metal Corrosion

Before discussing cleaning methods, it is essential to understand what metal corrosion is and how it affects artifacts. Corrosion is the gradual destruction of materials, typically metals, through chemical reactions with their environment. Different types of metals corrode in various ways:

Iron: Rust formation, a reddish-brown flaky substance, occurs when iron reacts with oxygen and moisture.
Copper: Develops a green patina (verdigris) when exposed to moisture and air over time.
Silver: Tarns to a black color due to the formation of silver sulfides when it reacts with sulfur compounds in the air.

Recognizing the nuances of corrosion is vital for selecting appropriate cleaning and preservation methods.

Initial Assessment of Artifacts

Upon retrieval of a metal artifact, performing a detailed assessment is crucial. Consider the following:

Material Composition: Identify whether the artifact is made of bronze, iron, copper, or silver, as each requires different cleaning methods.
Condition: Evaluate the artifacts physical state, checking for cracks, breaks, or loose parts that may affect its integrity.
Environmental Factors: Note any environmental conditions that may have contributed to the artifacts condition, such as moisture or soil acidity.

This assessment will guide you in determining the most effective cleaning approach.

Basic Cleaning Techniques

After assessing the artifact, the next step is to clean it. Below are recommended methods tailored to specific types of metals:

Iron Artifacts: Use a soft brush to remove loose dirt and corrosion. If rust is significant, consider soaking the artifact in a solution of 1:1 vinegar and water for an hour, followed by a light scrubbing with a toothbrush.
Copper Artifacts: Avoid abrasive materials which may scratch the surface. Instead, clean using a mixture of equal parts water, vinegar, and salt. Apply gently with a soft cloth.
Silver Artifacts: Use a dedicated silver cleaning cloth or a solution of baking soda and water. Mix to a paste and apply gently, making sure to rinse thoroughly afterward.

In all cases, thorough rinsing with distilled water is critical to avoid mineral deposits from tap water, which can cause further corrosion.

Advanced Cleaning Techniques

For severely corroded artifacts, advanced techniques may be necessary. Consider the following approaches:

Electrolysis: This method involves submerging the artifact in a solution (often sodium bicarbonate) and applying a low voltage current, which helps to remove rust safely from iron artifacts.
Chemical Treatments: Products such as rust removers or corrosion inhibitors may be used, but they should be selected based on the specific metal type and corrosion extent.

These advanced techniques should be applied with caution and ideally under the supervision of a conservator.

Preservation Methods

Once the metal artifact is cleaned, preservation becomes paramount. Select appropriate preservation strategies based on the artifacts material:

Coating: Apply a thin layer of wax or a specialized conservation product to protect the surface. This barrier can help prevent future oxidation.
Storage: Store artifacts in a stable, climate-controlled environment. Use appropriate materials, such as acid-free boxes and non-clorinated packing material.
Display: If exhibiting artifacts, ensure UV-filtering glass and controlled humidity levels to minimize deterioration.

Real-World Applications and Case Studies

Several prominent archaeological sites emphasize the importance of cleaning and preserving metal artifacts:

At the SS Garbo, after extensive underwater excavation, a significant number of metal artifacts were retrieved. A meticulous cleaning process using a combination of mechanical and chemical methods allowed for the safe restoration and later exhibition of these artifacts, showcasing their historical significance in maritime archaeology.

Plus, conservators at the New York Museum of Natural History implemented a pioneering electrolysis method to restore early 20th-century iron tools found at urban excavation sites, effectively removing corrosion without damaging the artifacts.

Conclusion and Actionable Takeaways

Cleaning and preserving metal artifacts is a specialized process requiring attention to detail and a thorough understanding of materials. To summarize:

Conduct a detailed assessment to understand the material and condition of the artifact.
Select appropriate cleaning methods based on the metal type and corrosion extent.
Use preservation strategies to ensure the longevity of the artifact.

By following these guidelines, individuals engaged in fieldwork can maintain the integrity and historical value of metal artifacts, contributing to broader archaeological knowledge and appreciation.