Kathleen M. Garland, Stephanie Spence, and R. Bruce North
Abstract
This paper will describe some tools for producing detailed, 3D printed restorations for ceramics that may also be applicable to other areas of conservation. Photogrammetry is a 3D imaging process that is relatively easy to do with standard photography equipment in the conservation lab, provided one has a computer with a sufficient processing capability. Agisoft PhotoScan was used to create three dimensional mesh models of several different ceramics that were in need of restoration. The project involved experimentation with available 3D modeling and sculpting programs. Autodesk Meshmixer, a free software system, was selected to digitally ”sculpt” and process the meshes for a 3D print in resin. The finished resin parts were then easily attached to the body of the ceramic and painted using conventional methods.
The ceramics in this study include a small Meissen porcelain with a missing right hand and eyeglass lens, a 12th century Persian ceramic with a missing handle, and an 18th century English delftware posset pot lacking sculptural elements on the lid. The use of 3D printed parts resolved a variety of problems commonly found in ceramic restoration, such as complex and simple modeling, shiny glazed surfaces, achieving fine detail on very small elements, mirroring of meshes to create a right hand from a digital model of the left, and the need for precise joins on complex break edges.
While the learning curve for using these programs is steep, familiarity makes the operator more efficient, and there are a number of advantages to printing these restorations instead of using conventional techniques. First of all, handling of the artifact is dramatically reduced, an important safety factor. Conventional modeling and casting of very small detailed parts, such as a missing porcelain hand, is challenging for many, and may require some creative interpretation by the conservator. However, with digital models, it is possible to provide a more “authentic” restoration. For example, a missing left hand can be created and articulated from a digital mesh model of the right hand. Thus, the restored right hand, as a mirror image of the original left hand, could be considered a closer iteration of the artist’s intent. It is also very easy to create a digital mesh of the “stump” or break edges of the ceramic and use this to make a nearly perfect match in the printed restoration.
One practical and timesaving advantage is that much of the imaging and printing work can be subcontracted to volunteers, students or contractors who have specialized digital skills. Sharing the highly accurate digital models based on laser scanning or photogrammetry will also make similar examples by the same artist or workshop easier to share, either for the purpose of loss compensation or study. The digital files are also available for future research. Finally, the use of 3D digital models allows for experimentation that is helpful in discussing positioning and articulation of restorations with curators. The techniques discussed here are likely to have applications beyond ceramic restoration.