Bone china figure fabrication using direct ink writing-type 3D printing technology

We carried out material and process optimization to fabricate a bone china figure using the direct ink writing-type 3D printing technology. To improve the viscoelastic properties of the bone china paste, we added PEG and glycerin and analyzed the rheological properties. The lowest viscosity was obtained when a mixture of 1 wt% PEG and 4 wt% glycerin was added to the paste, which resulted in excellent movement speed of the material in the system. A solvent content of 25% showed the best printing properties when water was used as the single solvent. In the ethanol-added solvent investigated to improve the shear yield strength, the best printing properties were observed for 40% ethanol. However, at an ethanol content of 50% or more, the drying rate increased excessively, and peeling and cracking between the layers were observed. The shell thickness was set as 4.8 mm or more considering that the thickness would be reduced in the post-treatment process. In the final bone china figure fabricated according to the aforementioned optimization, the concordance rate of the completed figure to the digital sketch was approximately 74% in the comparison including the surface curves, and 93% for the frame alone.