Step one

OBSERVE 1. Observe the mussel shell. It is made out of three main layers:

- the periostracum: the dark outer protective film made of conchiolin protein

- the ostracum: the middle layer

- the hypostracum: the inner iridescent part known as NACRE + the byssus: the bundle of filaments (beard) through which the mussel sticks to a solid surface

Step two

PROCESSING THE BYSSUS

1. Debeard the mussel removing the byssus with your fingers or with the help of a knife

2. Wash the byssus with soap trying to remove the bigger parts of shells remained attached

3. Leave the byssus dipped in vinegar for 3 days approx. to remove any residual fragments of shells

4. Rinse it again and let it air dry. You will get strong thin fibers ready to be used in your recipes

Step three

REMOVING PERIOSTRACUM: You might want to remove the outer film that covers the shell to use it in other recipes and to avoid it to burn in the next step of the processing. Do so:

1. After cooking the mussels, clean the shells removing the muscle and any residual organic part with the help of a knife

2. Wearing gloves, in a basin prepare a sodium hydroxide solution weighing 0,2 parts of sodium hydroxide in 10 parts of water

3. Soak the shells and leave them 3-5 days in the solution. Water will turn darker as the periostracum pieces detach from the shells

4. With the help of gloves and an abrasive pad remove the dark film that covers the shells and rinse them

5. Let the shells air dry

6. You can recover the periostracum film left in the solution using a strainer, rinsing it and letting it air dry

Step four

SPLITTING OSTRACUM FROM NACRE

1. Place the shells on a baking tray

2. Cook the shells in oven at 250 °C for up to 3hours. The two layers turn progressively yellowish until they split up

3. You can now collect them and process them separately as an option. Using the nacre you can add iridescent properties to your recipes