This page reports the afternoon of experimentations we had on June 24th with Chloé Lequette, a friend, designer & biomimicryist co-founder of Enzmye & Co. She taught me how to cook a material based on eggshells and starch-less flour she developed last year for the Designers Days in Paris, and we experimented further with this recipe, adding other ingredients.
Mix flour in excess of water and let it sit for a while.
Once you can see two fractions, a solid one sitting at the bottom of the flask, and some white water on the top, discard the water fraction and keep the solid fraction.
This step aims at dissolving the starch contained in the flour, and keep only the glutinous fraction of the flour.
Mix the glutinous fraction of flour with crushed eggshells.
The proportion changes the nature of the material. Chloé goes for 2/3 wet flour for 1/3 crushed eggshells, but she says that half-half is also fine.
Then, just let it dry overnight. You can accelerate drying by using a microwave. One minute at 1000 W is too much, but five minutes on the grill position were fine.
We ended up with slightly plastic objects of diverse shapes. They do not hold water very well and start to disagregate if they contain/are dipped in a liquid. This material is therefore more for decorative purposes, as a coating on vases, for instance.