How do underwater archaeologists excavate fragile materials?

Underwater archaeologists have to take extra care when excavating fragile materials due to the conditions and the potential for degradation over time. Here are the key techniques and methods they use to handle these delicate items:

1. Careful Site Assessment: Before beginning excavation, archaeologists assess the site thoroughly. This includes understanding the seabed composition, water depth, current, and environmental factors. A detailed survey often precedes excavation to map out where fragile materials might be located.
2. Sediment Stabilization: Fragile artifacts, especially those made from organic materials like wood, textiles, or bone, are often surrounded by soft sediments that can shift easily. Archaeologists may stabilize the sediment around the artifact with techniques like “wet sieving” or using fine mesh to carefully lift the artifact with its surrounding material.
3. In Situ Preservation: Sometimes, fragile materials are left in place and preserved in their original location to avoid damage. This may involve covering them with materials like tarps or plastic sheeting to protect them from further exposure to the water, or applying protective coatings that prevent deterioration.
4. Use of Specialized Tools: Archaeologists use specialized tools to carefully excavate fragile materials. These may include small hand tools like brushes, trowels, or even syringes to remove sediment. Additionally, they might use soft or flexible materials, such as rubber or plastic, to handle the artifact delicately without causing any harm.
5. Conservation in Water: For materials that are extremely fragile, underwater archaeologists often keep the artifacts submerged or in water during excavation to prevent air exposure, which can lead to cracking or dehydration. Water, especially in controlled environments, can help stabilize the artifacts and prevent them from collapsing.
6. Documenting the Excavation: Archaeologists use high-definition photography, 3D scanning, and detailed mapping before and during the excavation. This documentation allows them to gather as much information as possible without having to move the objects immediately, especially in the case of delicate finds.
7. Transporting and Conserving Artifacts: After the artifact is excavated, it is carefully transported to a conservation lab. There, it is often placed in controlled environments where temperature, humidity, and light levels are closely monitored to slow down degradation. Conservators may employ techniques like freeze-drying or chemical stabilization to prevent further damage.
8. Collaboration with Conservators: Underwater archaeologists often work closely with conservators who specialize in preserving materials from different environments. These specialists can provide advice on proper handling, cleaning, and long-term care for fragile materials, such as ceramics, textiles, or bones.

By using these techniques, underwater archaeologists are able to excavate and preserve fragile artifacts for study and display, often unveiling significant insights into ancient cultures and shipwrecks.