+
Materials
Factors such as temperature and humidity continue to affect the behavior of the biopolymers in the weeks, months, and years post-production. Over time the surfaces will curl and darken as the material continues to dry. The biopolymer prints will experience varying degrees of shape and color change that are accelerated and exaggerated by higher temperatures and dryer environments. Hydrogel mixtures containing more significant concentrations of chitosan will typically exhibit higher degrees of color, shape, and structural change more rapidly.
As the printed hydrogels dry, the materials darken in color. The standard pectin chitosan hydrogel formula dries into a light orange-yellow color. Over time, the prints will gradually change from a dark orange into a reddish-brown and eventually to a very dark brown. This behavior affects material mixtures that contain organic pigments to darken chitosan hydrogels containing turmeric, beet, spirulina, and matcha powder. Materials mixtures with pigments such as charcoal or indigo will not turn noticeably darker primarily because of their already dark appearance. In contrast, pectin material mixtures without chitosan will often lose their vibrant colors and turn lighter with a whitish surface coating when exposed to more humid environments.
As the printed hydrogels dry, the materials shrink. This process begins immediately after the biopolymers have been extruded onto the print bed with the most noticeable thinning and shrinkage occurring during the first 48 hours. Additional moisture loss over time will cause the solidified surfaces to continue to shrink more slowly. The difference in rates of shrinkage of a top surface vs. a bottom surface will cause materials to deform from being flat to curved. The deformation is partially caused by adjacent regions that exhibit different levels of water loss. Exposure of a top surface to more air and heat will allow it to dry faster and deform more than the bottom surface. Pectin formulas containing chitosan and calcium will warp the most dramatically in environments with higher temperatures.
As the printed hydrogels dry, the materials become more rigid and brittle. With the gradual loss of moisture, the biopolymer surfaces lose their initial flexibility. Material formulas without chitosan will retain their flexibility for extended periods, while formulas containing calcium carbonate, cellulose, and chitosan will become rigid and brittle much more quickly. The pattern of the toolpaths and the air bubbles formed during extrusion and drying can create varied surface textures. Additionally, material formulas containing cinnamon and chitosan will exhibit a rougher surface texture.
As the printed hydrogels dry, the materials darken in color. The standard pectin chitosan hydrogel formula dries into a light orange-yellow color. Over time, the prints will gradually change from a dark orange into a reddish-brown and eventually to a very dark brown. This behavior affects material mixtures that contain organic pigments to darken chitosan hydrogels containing turmeric, beet, spirulina, and matcha powder. Materials mixtures with pigments such as charcoal or indigo will not turn noticeably darker primarily because of their already dark appearance. In contrast, pectin material mixtures without chitosan will often lose their vibrant colors and turn lighter with a whitish surface coating when exposed to more humid environments.
As the printed hydrogels dry, the materials shrink. This process begins immediately after the biopolymers have been extruded onto the print bed with the most noticeable thinning and shrinkage occurring during the first 48 hours. Additional moisture loss over time will cause the solidified surfaces to continue to shrink more slowly. The difference in rates of shrinkage of a top surface vs. a bottom surface will cause materials to deform from being flat to curved. The deformation is partially caused by adjacent regions that exhibit different levels of water loss. Exposure of a top surface to more air and heat will allow it to dry faster and deform more than the bottom surface. Pectin formulas containing chitosan and calcium will warp the most dramatically in environments with higher temperatures.
As the printed hydrogels dry, the materials become more rigid and brittle. With the gradual loss of moisture, the biopolymer surfaces lose their initial flexibility. Material formulas without chitosan will retain their flexibility for extended periods, while formulas containing calcium carbonate, cellulose, and chitosan will become rigid and brittle much more quickly. The pattern of the toolpaths and the air bubbles formed during extrusion and drying can create varied surface textures. Additionally, material formulas containing cinnamon and chitosan will exhibit a rougher surface texture.