Image Credit : Research Delft University of Technology
Preparation step to obtain mussel shell powder:
1. Wash the mussel shells and remove remaining waste.
2. Cook the shells for 15 minutes.
3. Heat the shells for 1 hour at 200 degrees in the oven. This will make the shells more brittle.
4. Grind the shells into a powder.
5. Sieve the grinded shells to obtain a powder with particle size of 75 micron (note: 125 micron should also work).
Paste preparation:
1. Measure 0.3 gram of Sodium-Alginate (3wt-% of paste)
2. Measure 3.6 gram of water (36wt-% of paste).
3. Add water to the alginate and stir until a gel has formed.
4. Measure 6.1 gram of mussel shell powder (61wt-% of paste)
5. Add powder to the binder
6. Stir until the ingredients are well mixed into a smooth and homogeneous paste
3D printing:
1. Fill syringe with paste
2. 3D print desired shape with paste
3. Dry object at room temperature until completely dried out
Post processing step to obtain water-resistant material with ion cross-linking
1. Prepare 2% solution with calcium chloride and water
2. Submerge printed object in the calcium chloride solution for at least 30 minutes (longer is also possible)
3. Dry object at room temperature until completely dried out
4. Your object is now water-resistant, but will become ductile when submerged in water.
Reverse ion cross-links to retain a printable paste after use: Sodium citrate solution:
1. Weigh object
2. Calculate 2 wt-% and 50wt-% of the weighted object.
3. Measure the amount of 2wt-% for sodium citrate
4. Measure the amount of 50wt-% for water
5. Add water to the sodium citrate and stir until dissolved
Dissolve object:
1. Grind weighted objects in small pieces, for example with a mortar and pestle.
2. Add ground pieces to the prepared sodium citrate solution.
3. Stir until a homogenous paste is retained. A (laboratory) mixer is recommended for this. Make sure the paste is homogenous and smooth again.
4. The paste is now ready to 3D print again.
