Can You Duplicate Pottery Sherds?

ByScarlett Evans

Introduction

Pottery sherds are broken fragments of ceramic vessels, containers and objects found at archaeological sites. The study of pottery sherds is a key aspect of archaeology as it can provide insights into the pottery production techniques, trade networks, social and economic organization of past societies. Sherds remain even when whole vessels do not survive, making them an abundant source of information.

Archaeologists analyze features of sherds such as their shape, size, decoration, glaze, etc. to classify them into types and determine their origins. Sometimes archaeologists may want to study or display complete vessel profiles, requiring sherds to be reassembled through restoration. Other times, duplicates or reproductions of sherds may be made for comparative analysis, teaching purposes, or to minimize handling of fragile originals. Techniques for duplicating sherds include molding and casting, 3D scanning and printing, as well as freehand reproduction.

History of Studying Sherds

Archaeologists have been studying pottery sherds closely since the 19th century when systematic archaeological excavations first began. Early archaeologists like Heinrich Schliemann, who excavated Troy, and Sir Arthur Evans, who excavated Knossos, realized that pottery styles changed over time and could be used to date sites and artifacts (Pottery Sherds in the Dirt – Part 2). By studying the shapes, styles, materials and manufacturing techniques of pottery fragments, archaeologists developed typologies and chronologies for ancient pottery that allowed them to date sites and track the spread of ideas and trade.

Some key developments and discoveries made through analyzing sherds include:

Techniques for Analyzing Sherds

Archaeologists use a variety of techniques to analyze pottery sherds and extract information about their date, origin, and use. Some common techniques include:

Visual examination – Looking at the sherd’s physical characteristics like color, texture, inclusions, and vessel shape can provide clues about its date and origin. Subtle differences in manufacturing methods over time or in different regions allow archaeologists to categorize sherds.

Petrography – This technique analyzes the mineral and rock inclusions in the clay to identify the geological source of the raw materials. Identifying the clay source can indicate where the pottery was produced.

Residue analysis – Chemical tests are used to identify traces of organic residues absorbed into the clay. Finding lipid residues from animals or plants can reveal what the vessel was used for.

Thermoluminescence – Measuring light emitted from sherds when heated can date when the pottery was fired during manufacture. The last time the clay was exposed to high heat sets the “clock” for thermoluminescence.

These scientific analytical techniques combined with visual examination allow archaeologists to get a detailed understanding of a pottery sherd’s origins and use (An Exploration of New Methods of Ceramic Analysis Examining Pottery Sherds From American Samoa Using Computed Tomography, Physical Examination, and Residue Analysis, 2019).

Reasons for Duplicating Sherds

There are a few key reasons archaeologists and museums may want to duplicate pottery sherds:

Completing partially damaged artifacts – Sherds are often fragmented and incomplete. By scanning and duplicating sherds, researchers can digitally reconstruct whole vessels from partial pieces. This allows a more complete analysis of artifacts (Source).

reconstructing vessels from sherds reveals more information

Recreating lost or fragile originals for display/handling – Many ancient sherds are too delicate or valuable to be regularly handled or exhibited. Creating duplicates allows museums to display convincing replicas while keeping originals safe in storage (Source). Duplicates also enable wider access to artifacts that may have been damaged, decayed, or lost over time.

Making Clay Duplicates

One of the most traditional methods for duplicating pottery sherds is by handmaking clay duplicates. This involves carefully selecting an appropriate clay body that matches the physical properties of the original artifact. According to archaeologist Jim Watts, “an ideal clay for duplication will shrink at a similar rate to the original and can be fired to a comparable hardness.” 1

Once the clay is prepared, the sherd can be used as a template to cut out the shape. Paying close attention to the contours, thickness, and dimensions of the original helps produce an accurate duplicate. Subtle details like surface markings, imperfections, or decoration can be mimicked using modeling tools. A practiced hand can delicately incise lines, add coils of clay, or stamp patterns into the soft surface.

Firing is also an important step in completing a clay duplicate. Choosing a firing method and temperature range comparable to how the original artifact was processed helps achieve a similar look and feel. This helps make clay duplicates nearly indistinguishable from ancient pottery. With some skill and practice, handmaking replicas allows full customization and control over every step of the process.

Using Molds

One of the most common techniques for duplicating ceramic sherds is by using molds. This involves making an imprint of the original sherd to create a negative mold, which can then be used to cast multiple duplicates.

To make the mold, the sherd is pressed into or coated with a liquid molding material like plaster, silicone rubber, or resin. These materials harden into a solid but flexible mold that captures the shape and surface details of the original artifact. Plaster is inexpensive and easy to use, but silicone and resin molds are more durable for multiple castings (Ceramic Mold Casting, 2022).

Once the mold has set, a casting material is poured or pressed into the mold cavity to create the duplicate. Clay slip, resin, plaster, or wax are common casting materials. The properties like color and texture can be adjusted to match the original sherd. The casting is left to cure before removing it from the mold (Zhushchikhovskaya, 2021).

The flexibility of the mold allows the duplicate to be removed without damage so the mold can be reused. This makes molding and casting an efficient way to produce multiple identical copies for study. Care must be taken to achieve the right material properties so the duplicate resembles the original sherd in weight, feel, and durability. With refinement, high fidelity duplicates can be attained (Rose, 2023).

Overall, molding and casting provides a practical approach to duplicating ceramic sherds with control over the material properties. The initial mold making takes time and skill, but allows efficient replication once the mold is prepared.

3D Scanning and Printing

3D scanning technologies like photogrammetry and laser scanning allow researchers to create detailed 3D digital models of pottery sherds (Karasik, 2008). Photogrammetry uses a series of overlapping photographs taken from different angles to construct 3D models. Laser scanning directs a laser at the sherd’s surface and measures the reflection to map its shape and topography. Both methods produce high-resolution 3D models that capture the sherd’s form and surface details with precision.

Once a 3D model is created, it can be used to 3D print physical duplicates of the original sherd. The models are loaded into a 3D printer, which builds up the duplicate layer-by-layer out of plastic, resin, or other materials. The resolution of consumer 3D printers today allows for remarkably accurate printed duplicates down to the finest surface textures (Yu, 2019). As 3D scanning and printing technologies continue to improve in speed, cost, and accuracy, their potential for efficiently duplicating large collections of ceramic sherds grows.

Comparing Duplication Methods

There are three main methods for duplicating ancient pottery sherds: clay modeling by hand, using molds, and 3D scanning/printing. Each method has its own pros and cons.

Clay modeling by hand allows for meticulous recreation of the sherd’s shape and texture. However, it is very time consuming and requires an experienced ceramicist. Subtle details like the thickness of the walls can be difficult to precisely duplicate (“Replicate Any Ancient Pottery Using These 3 Methods”).

Making molds from the original sherds can speed up the duplication process. The molds preserve the shape accurately. However, some texture and fine details may be lost. Molds can degrade over time. And the duplication relies on the quality of the mold (“An Experimental Comparison of Impressions Made from Replicated Neolithic Linen and Bronze Age Woollen Textiles”).

3D scanning and printing provides a high tech option for precisely duplicating sherds. Scans capture the complete geometry in digital form. Prints can recreate it in various materials like clay. But access to scanning equipment can be limited. And prints may not fully replicate surface textures.

Authentication of Duplicates

As reproductions and replicas of ancient pottery become more sophisticated, it’s important for researchers, collectors, and museums to have methods for authenticating whether a fragment is an original or a duplicate. Careful labeling, cataloging, and marking of duplicates helps avoid passing off reproductions as genuine artifacts. Scientific testing techniques can also verify the authenticity of ceramic pieces.

When creating duplicate sherds, it’s critical to permanently mark them in an unobtrusive location, such as the underside, and clearly label them as reproductions. Maintaining detailed records of all duplicated fragments prevents misrepresentation as originals. Many institutions follow established cataloging systems to log key details like the artifact’s provenance and any repairs or restoration.

Advanced analytical methods can also authenticate ancient pottery. As described in research published in Nature Communications (https://www.nature.com/articles/s41467-018-06335-6), mass spectrometry techniques can identify ancient proteins preserved in the clay, definitively verifying whether a sherd dates to an archaeological site or originates from a modern duplication. Such protein analysis provides a reliable scientific method for authenticating ceramic artifacts when questions arise about their legitimacy.

Conclusion

Duplicating pottery sherds can serve several important purposes, but must be done responsibly. The main techniques are molding, 3D scanning and printing, and freehand imitation. Molds can accurately reproduce surface details, but limit the scope of what’s duplicated. 3D scanning captures complete form and texture, but requires expensive equipment. Freehand imitation is accessible but less precise. Responsible duplication requires acknowledging copies, respecting cultural significance, and obtaining permission. Each method has tradeoffs between cost, accuracy and ethics. Overall, duplication provides valuable opportunities for research, education, preservation and repatriation when undertaken conscientiously.

Creating accurate duplicates expands access to artifacts while protecting originals. Digital and physical copies enable wider study and handling without damaging rare finds. Duplication also aids repatriation efforts by letting museums return sensitive items to indigenous communities, while retaining replicas for display and research. However, copying raises concerns about authenticity, cultural appropriation, and commercialization. Responsible duplication involves transparency regarding copies, consultation with stakeholders, and avoiding commercial exploitation. With care, duplication emerges as an ethically complex but useful tool for broadening understanding of ancient cultures while stewarding their priceless heritage.

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