# Enhancing 3D-Printed Clay Models for Heritage Restoration Through 3D Scanning
## 3 Results  
After creating the digital twins using the EinScan Pro HD 3D scanner, 3D printing is carried out for three representative ceramic elements selected from the Plaza de Espana in Seville (Figure 6). Each element, characterised by its complexity and ornamental detail, is reproduced in a fairly short time per piece. The printing process, performed with clay, proved to be highly efficient in terms of both time and quality, offering advantages compared to traditional ceramic restoration techniques. Both clay pastes used behaved adequately in the impression with no remarkable differences. The traditional method of producing ceramic pieces typically requires creating plaster molds from master models sculpted by artisans [66]. This approach is both time-consuming and costly, with the process of developing the master model and molds taking anywhere from days to weeks, depending on the complexity of the design. Additionally, the molds have a limited lifespan, necessitating their replacement after multiple uses, which further increases production time and costs. In this method, ceramic masses are mixed in a ball mill for 24 h, and after shaping, the pieces undergo natural drying followed by sintering at 1200 \({}^{\circ}\)C for several hours [45]. While this process ensures material consistency and durability across a range of firing temperatures, it relies heavily on artisanal skill and presents challenges in achieving efficiency and precision in reproducing intricate details. In contrast, 3D printing offers a significant advantage by enabling the direct fabrication of unique pieces, eliminating the need for mold creation. This not only enhances efficiency but also allows for precise digital control over the design and material properties, thus providing greater flexibility in producing highly detailed and customized ceramic artefacts. Moreover, once the digital model is established, production can be scaled without the drawbacks associated with traditional mold-making, making 3D printing a more viable solution for unique or damaged pieces that require restoration. Below is a detailed table that records the printing, drying, and firing times for each of the ceramic pieces selected for this study (Table 2). This table allows for an analysis of how these variables are affected by the size of the pieces, providing a comparative view on the efficiency and viability of the 3D printing with clay methodology based on the dimensions of the objects. By evaluating these times, it is possible to determine the extent to which size influences the overall process, providing essential data for the future optimization of restoration techniques using additive manufacturing. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Case Study**} & **Printing** & **Drying** & **Drying** & **Firing** & **Firing** \\  & **Time** & **Temperature** & **Time** & **Temperature** & **Time** \\ \hline
1 & 97 min & 105 \({}^{\circ}\)C & 24 h & 980 \({}^{\circ}\)C & 280 min \({}^{1}\) \\
2 & 335 min & 105 \({}^{\circ}\)C & 24 h & 1020 \({}^{\circ}\)C & 320 min \({}^{1}\) \\
3 & 200 min & 105 \({}^{\circ}\)C & 24 h & 1020 \({}^{\circ}\)C & 320 min \({}^{1}\) \\ \hline \hline \end{tabular} \({}^{\dagger}\)Time at maximum firing temperature.  
\end{table} 
Table 2: Printing data from the case studies: printing time, drying and firing times and temperatures. Figure 6: Results of the process (from left to right) 3D scanning, post-processing and 3D printing. (**a**) Case study 1: Representative baluster of balustrades; (**b**) Case study 2: Pinnacle in water sheet; (**c**) Case study 3: Pinnacle in ornamental fountain. One of the main advantages observed is the reduction in restoration times. While traditional ceramic restoration techniques can require days or even weeks of manual work, 3D printing allows for the precise creation of replicas within minutes. This decrease in production time not only optimizes the restoration process but also reduces associated costs by minimizing labour and material requirements [45].