Step one

A day before, prepare a 2% alginate solution by mixing 200ml of water with 4 grams of sodium alginate. Leave the alginate solution to hydrate for 24 hours. In addition, dry and sieve the coffee grounds to have a consistent material. 

Step two

Mix the coffee grounds with 40 grams of the hydrated 2% alginate solution an 10 grams of glycerol. Carefully stir the mix, avoiding the creation of bubbles, until it is fully integrated.

Step three

Pour in a mould and tap the sides to release any remaining bubbles and leave it for 15 minutes to set. 

Step four

After that, add gently on top of the mix the vinegar. It will start reacting and coagulating with the alginate. Leave it for 15 minutes and then slightly separate the mix from the mould, leaving space for the vinegar to penetrate the sides. Wait for an hour.  Then take the sample out of the mould and turn it around to allow the vinegar to reach the other side of the biocomposite. Leave it for an hour more. 

Step five

Take it out of the mould, rinse it under tap water to clean the vinegar and leave it to dry for 1 -2 days depending on the humidity and temperature of the environment. For an ideal dry, it can be dry in a dehydrator at 35ºC for 12 hours.