- grinded musselshells
- 7,5% (m/v) sodium alginate solution
- 2% (m/v) calcium chloride solution
- clean the shells
- remove the periostracum (optional)
- grind the shells
- prepare the alginate solution
- mix and mold
- post treatment: cross-linking
CLEAN THE BYSSUS
- After cooking the mussels, clean the shells removing the muscle and any residual organic part with the help of a knife.
remove the periostracum (optional)
To remove the dark layer that covers the shells and make them easier to grind in the following step:
- Wearing gloves, in a basin prepare a sodium hydroxide solution weighing 0,2 parts of sodium hydroxide in 10 parts of water;
- Soak the shells and leave them 3-5 days in the solution. Water will turn darker as the periostracum pieces detach from the shells. The shells become more brittle;
- With the help of gloves and an abrasive pad remove the dark film that covers the shells and rinse them;
- Let the shells air dry.
grind the shells
In sodium hydroxide pre-treatment (see step 2 – optional-), the shells become more brittle. You can also put them in the oven for a while to make them easier to grind.
TIPS TO GRIND THE SHELLS:
- I normally use a mortar to start breaking the shells;
- You would need a blender to make a finer powder. My advice is not to use an expensive one cause the shells can be tough to grind and it could get damaged;
- Using strainers with different sizes of the holes you get coarser of finer powders. 1mm mesh size is good.
PREPARE THE ALGINATE SOLUTION
- Pour water into a tall container with a lid and add the alginate;
- Mix well with a whisk. It can help you closing the lid and shaking the container for a couple of minutes;
- Leave the solution in the fridge overnight to make it homogeneous and to let out the air bubbles.
MIX AND MOLD
- Weight the shells powder and the alginate solution.
With 3 parts of grinded shells (e.g. 300gr) and 1 part of alginate solution (e.g. 100gr) you get a compound you can mold with your hands. On the other hand, decreasing the percentage of powder (up to 1 part of shells and 1 part of alginate) you get a less dense consistency more suitable to be poured into a mold.
- Mix well with a spoon to make the mixture as homogeneous as possible;
- Mold the mixture into a shape;
- Let it air dry. You can also use a dehydrator or put the pieces in the oven at 35°C to shorten the drying time. But the more liquid is the mix, the more it will tend to crack if subjected to temperature changes.
- Prepare a 2% calcium chloride solution with water;
- Dip the shells composite in the calcium chloride bath for 10-20min;
- Let it air dry. It is now water resistant (but will absorb water if soaked).