10 Things to know about Agar Agar Bioplastics
The main (bio)material we used for our latest Bio Uncu Maker is based on Agar agar, a gelatinous substance made with an extract of red algae abundant on the Pacific coast of Peru and Chile.
Did you know that this biomaterial is biocompatible with human skin? And the fact that this considerably reduces the probability of an allergic reaction occurring?
Another amazing fact is that Agar agar bioplastics affect touch capacitive screens! Amazing, right?!
Our research and development process began with the generation of the biomaterial, which brought us many lessons learned that we want to share with our future bio makers:
- Tip 1: Agar agar’s Powder form dissolves faster and more evenly
Agar is available in three different formats (bars, granules, and powder). Because agar needs to be heated to 90°C to dissolve properly in liquid, the powdered form is easiest to work with. If you are using bars or flakes, we suggest you break them into a powder first, using a coffee or spice grinder. The powder form dissolves faster and more evenly.
- Tip 2: Start with a basic recipe and then try different combinations of Agar agar, Glycerine and Distilled water.
An additional thing to know is that a bioplastic made with Agar agar may ‘sweat’ when in humid weather. To prevent this, you may add a little bit of corn starch (corn flour) with Agar agar into the liquid that you are cooking it in.
There are many recipes, but you start your journey with those ingredients that you can find in your community or closest ecosystem, but also keep in mind what type of possible applications of your new biomaterial you can explore and validate further.
- Tip 3: Check Ph of liquids vehicle and natural dyes
If you’re going to add some natural dyes, the best way to include them in your recipe is to add them at the end of the cooking process. In addition, it is very important that you monitor the level of pH of the liquid solution because Agar agar is sensible to acid pH levels and to the concentration of Calcium in the solution. Therefore for all your liquid ingredients make sure you always use filtered water.
Take in consideration that some natural colors can be thermosensitive (Spiruline and beet for example), therefore you must add them at the very end of your cooking process to prevent any fading.
- Tip 4: Documentation and Registration of your Bioplastic Journey
This is key for documenting all the lessons learned during your bio-making journey. Excel sheets can help at the beginning for effectively following up a sample’s progress. Don’t forget to include photos. All the morphological transformations will be key for identifying each resulting biomaterial’s possible applications: rugosity, transparency, brightness, flexibility, hardness and density.
- Tip 5: Natural dyes preparation
Colour’s selection depends on the concept of your bio project. But here you can find some very useful guidelines for preparing your natural dyes. For example, for our Bio Uncu project we decided to go for an Andean Palette of Colours made with Purple Corn and Annatto.
- Tip 6: Bubbling control and heating
Having in mind Agar agar bioplastics cool quickly, it is very important to control bubbling before pouring the mixture into the molds. You can stir the bubbles with a spoon or pass the hot mixture through a colander. If you want to remove them in a professional manner, there is specialized equipment for it called Vacuum Bubble Removers.
Another very important method is by controlling the temperature of your preparation, just make sure it does not exceed the 90-95 Celsius degrees.
- Tip 7: Surfaces of molds
Ideal surfaces for Agar agar bioplastics are glass, textiles with high thread counts of 250 or more and high-density textiles. It will depend on the type of transparency and texture you would like to accomplish.
- Tip 8: Cooking Time and Volume
Cooking time will depend on the volume of your mixture. For samples between 300ml to 500ml the cooking time over moderate heat is approximately 30min and for volumes greater than 500ml the ideal cooking time is 40 to 45min. Do not forget to control the temperature and shake the mixture continuously to avoid the formation of lumps.
- Tip 9: How to make an Agar agar bioplastic stronger
Researchers at Tuskegee University in Alabama found that adding nanoparticles made of eggshells to bioplastic increases the strength and flexibility of the material, potentially making it more attractive for use in the packaging industry.
You may experiment with adding other additives (fibers, organic waste; etc) that will make your samples more tough and resistant.
- Tip 10: The drying and testing process
Agar agar bioplastics shrink a lot in size and thickness over time, and if left in a mold where it’s connected to wooden edges, will form cracks in the center. So, make sure to cut the agar free from the edges of the mold after the first 24 hours of setting.
Wait and dry, typically 2-4 days before you remove your samples from the mold. The morphologic and biomechanical tests of your samples must be done after the second week though.
One very important thing is to let the samples dry in a well ventilated, insulated and dry environment to prevent the samples from mold.
I hope these tips will be useful for you as a good starting point for your journey as future bio makers!
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