I met a student biomedics who wants to help me to extract the alginate out of the seewead. We will try this in 2 weeks. Meanwhile 'I' exercised with papier mache and agar agar.
step 1: tear paper and put it into water
step 2: preparing the agar agar
step 3: glue the paper with the agar agar on a balloon. Because of the vacation I had enthousiastic children to help
The result: the agar agar has the same function as you use glue for making papier mache