THE_BASIC_RECIPE

The recipe for our coffee leather is from the book „The Pandemic Cookbook“ by Prof. Dr. sc. Manuel Kretzer and the Materiability Research Group.

The basic recipe:

2g coffee grounds

1g reed fibers

2g glycerin

2g sodium alginate

7g calcium chloride

133g water

Since we did not have reed fibers available, we decided to test which fibers available in the lab would yield the best results.

THE_FABRICATION

Weigh and mix the coffee grounds, glycerin, sodium alginate, fibers, and 33g of water in a container. Additionally, mix a calcium chloride solution from 7g of calcium chloride and 100g of water and fill it into a spray bottle.

Next, pour the mixture into a container and spread it out. To remove moisture, spray the mixture with the calcium chloride solution. After 5 minutes, turn the mixture over and spray the other side. Then, rinse everything off.

OUR_EXPERIMENT

In our first experiment, we used hay fibers instead of reed fibers in the basic recipe. We decided to place our samples in the press for a week. However, since they could not dry properly in the press, our first samples developed mold.

After our experiment with hay fibers, we decided to use C320 fibers, sisal fibers, shives, oat flakes, and sawdust for our further experiments. Additionally, we added 2% kalium sorbate to the solid mixture.

CONCLUSION

By using different fibers, we obtained leather samples with varying flexibility. We achieved what we considered the best result with the C320 fibers, as it most closely resembled leather. For example, with sawdust or oat flakes, the samples became so hard and inflexible that some even broke. Pressing the 320 mixture revealed another dimension: the thickest parts of the material became more smooth and shiny under pressure. This result led us to many more ideas how one could continue the experimenting on this material. It was an interesting experience to research sustainable materials and create a vegan leather alternative.

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