Making composite materials from food waste & Algae
a detailed open source OD&M project by Midushi Kochhar
The 12 week research residency at Green Lab gave me the chance to experiment with material derivatives of red & brown algae and test its application for everyday objects.
My goal was to combine byproducts of the food industry with bioplastics/ bio-hardeners to make functional products. I utilised common food waste such as egg shells and tea leaves, that were accessible from a home environment and more industrial waste such as chicken feathers from the poultry industry. Combining these byproducts with natural algae based binders (agar agar* & alginate*) I was able to create new and durable materials.
* Agar-agar is a jelly-like substance, obtained from red algae. Agar forms the supporting structure in the cell walls of certain species of algae. It’s a common food ingredient and also used as alternative to gelatin.
* Alginate is a polysaccharide from the cell walls of brown algae where through mixing with water it forms a viscous gum. Its commonly used in casting as the hardening agent as it binds well with calcium carbonate.
Research into using algae as a bio material to create alternatives to single use plastic is increasing and I worked with this idea in the creation of a set of ‘short life span’ products that could be used within a food context.
Fig 1. Eggware products
Material 1- Eggware
This ceramic-like material is made from ground eggshells and alginate. Its off-white in colour and has a slightly porous texture making it ideal to be used for disposable tableware. With further development and research into natural glazes the material could become more durable.
- 20g Waste Eggshells
- 5g Alginate
- 22ml Water
- Mixing Bowl
- Mould (3D printed or any plastic mould)
- Weighing Scale
Preparation of eggshells:
- Collect as many eggshells as you need from your home, neighbours cafes etc.
- Wash them thoroughly in water
- Place in a pan with fresh water and bring them to the boil, let them boil for 15 minutes
- Wash again to get rid of any egg residue
- Place them in the oven at 100 degrees for 15mins to dry them out and make them brittle. You don’t want the eggshells to burn so keep an eye on the temperature and timing as this varies from oven to oven
- Grind the eggshells down to the tiniest particles possible
- Pass the powder through a sieve and dispose off the big particles and egg membrane
Fig 2. Eggware moulds
Making the material:
- Sieve the alginate into a mixing bowl
- Add the water to the bowl and mix thoroughly so that there are no lumps
- Gradually add the eggshells until a thick slurry is formed and all the ingredients are mixed well
- Pour/ place the material with a spoon in a mould and leave it to dry
- Depending on the thickness of the sample, it can take up to 30 hours if air-dried. You can also dry it in the oven to speed up the process at a low temperature with the fan on
Fig 3. Egg cup
Material 2- Feather & Tea Plastic
The same recipe and method applies to both the feather & the tea composite – just with the one ingredient change depending on whether you are using feathers or tea.
You can also add any fibrous substance to the recipe and to get different results.
Shrinkage is a material property of Agar- Agar and as the water evaporates from the mixture, the material warps and shrinks tremendously. By adding fibrous material one can limit that shrinkage by leaving no more space for agar-agar to escape.
Fig 4. Feather Plastic sample
Fig 5. Tea leaves Plastic sample
My aim was to add value to food waste. For this purpose I mixed the feathers/ tea leaves with Agar- Agar. The resulting material can be used for disposable tableware or even more durable objects like lamps or surface material etc.
- 15g Agar Agar
- Desired amount of Feathers or Tea leaves
- 15g Flour (Optional- makes material stronger)
- 250ml Water
- 2 saucepans
- Weighing Scale
- Baking Paper
- Heat Press/ Heavy object
Fig 6. Process for Feather plastic recipe
Fig 7. Feather plastic sample
- Place the saucepan on the stove with the water
- Add the agar-agar and flour and bring the mixture to boil whilst stirring continuously
- Remove the pan from stove and pour the contents into the other pan
- Add the feathers/tea leaves gradually and keep mixing until the consistency feels right
- Place on a flat baking sheet and cover with baking paper
- Cover all the sides and place it under high pressure – use weights or something similar (no heat)
- Take it out from the press after 1 hour and let it air dry. The material will warp slightly due to shrinkage, as that is a property of agar-agar
- Once completely dried, place under heat/hydraulic press to make it completely flat and smooth
Fig 8. Initial Agar bioplastic sample
To find out more and follow my development of this project head to my wesbite: