Beginners guide to cooking bioplastics

Beginners guide

On this page you will find the necessary information and two easy recipes to get you going. Lab Pastoe also offers an in-depth course on making biomaterials, on two consecutive Wednesday evenings from 18:30 - 21:30. Please see the reservation tool for upcoming events or send an email to labpastoe@hku.nl.

What are bioplastics made of?

As with 'industrial' plastics, bioplastics are made by combining a **polymer **to make the material strong, with a plasticizer to make the material flexible, and something to mix and dissolve the two in. Extra ingredients can be colorants and fillers, to give the material color, texture and added characteristics such as sturdiness, ferromagnetism or conductivity. Over the years we learned that a few drops of essential oil help prevent bacterial and fungal growth.

Biopolymers we often use are gelatin, agar, alginate, chitine, cellulose, carrageenan and starch. Plasticizers we use are vegetable glycerine and sorbitol. We mix and dissolve these ingredients in water.

As colorants we often use natural dyes, teas, food colorings or mica powders, and as optional fillers we use dried organic debris or (food) waste materials such as coffee, eggshells, sawdust, wool, textiles etc. We have a collection of all of these, some for sale, some free to use. Please ask staff about it.

Which tools do I need?

To cook bioplastics you will need a scale to weigh ingredients, an electric or induction cooker, a pan, a wooden spoon to stir, a measuring beaker and a cooking thermometer. All of these you can find in the cabinet in the washing-up / screenprinting room at Lab Pastoe.

You will also need a mold to cast your material in or on. The easiest way to cast flat materials is to use a wooden embroidery hoop, in which you clamp some pvc plastic (which can take heat) or waterproof textile. You can find these in the washing-up / screenprinting room or under the drying table at Lab Pastoe.

== The upside of using an embroidery hoop, is that the bioplastic will stick to the wood, but not to the plastic. This means that after your material gellifies enough (about 24-48 hours), you will be able to remove the outer hoop and the plastic from your material, and leave the material attached to the inner hoop to dry upright, with air able to flow on both sides of your material, speeding up the drying process. ==

Assembling ingredients and cooking

You can find all polymers, glycerine, colorants and fillers in the window cabinet in the office at Lab Pastoe. Please ask staff which are free to use, and which have a price.

To start, you can choose one of these two easy recipes, based on gelatine (not vegan, easier to use) or agar (algae-based, vegan):

Biosilicone (gelatine-based)
This is a flexible bioplastic that can be also used in the sewing machine to embroider on. Ingredients for a medium-sized embroidery hoop:

Gelatine 48 gr
Glycerine 24 gr
Water (or dyed water) 240 ml
Two drops of essential oil

Assemble your ingredients, your mold/hoop and tools. Mix the gelatine with the cold water in your pan by stirring. Once dissolved, start heating up the mixture to maximum 80 degrees and add the glycerine and essential oil. Keep the mixture between 60-80 degrees and stir gently (to avoid bubbles) for about 10-20 minutes. If there is froth or foam on your mixture, remove it with a coffee filter, kitchen paper or a (froth-)spoon. Take the pan off the heat and let the material cool for a couple if minutes while stirring gently, until it gels a little but is still liquid, like syrup. Then cast in your hoop. Leave to dry in a ventilated area.

!! Always add a note with your name, material and date to your material when it is drying at Lab Pastoe. It is your own responsability to keep an eye on the drying process. After 10 days, materials that have not been picked up will be remelted and used again.

Agar bioplastic (algae-based)
This is a very flexible foil. Ingredients for a medium-sized embroidery hoop:

Agar 9 gr
Glycerine 12 gr
Water (or dyed water) 240 ml
Two drops of essential oil

Assemble your ingredients, your mold/hoop and tools. Mix the agar with the cold water in your pan by stirring. Once dissolved, start heating up the mixture to about 70 degrees and add the glycerine and essential oil. Keep the mixture on this heat and stir gently for about 10-20 minutes. Take the pan off the heat and let the material cool for a couple if minutes until it gels a little but is still liquid, like syrup. Then cast in your hoop. Leave to dry in a food dehydrator at lowest temp, near a heater or in a ventilated area.

Have a look at this cooking video from Fablab Barcelona that also uses this recipe (slightly other amounts, because of another size hoop they use):

!! Always add a note with your name, material and date to your material when it is drying at Lab Pastoe. It is your own responsability to keep an eye on the drying process. After 10 days, materials that have not been picked up will be remelted and used again.

Drying biomaterials

After about 24-48 hours (for agar it can take longer) take off the outer hoop and peel your bioplastic (which is now still attached to the inner hoop) off the plastic or waterproof fabric. If you find that it is not strong enough to do so, leave it to dry for another 8 hours. Clean the hoop and plastic with hot water, dry and store back in the crate. Dry your material upright in the hoop for another 5 or 6 days in a ventilated area. When completely dry (no longer cold to the touch) cut it out of the inner hoop. Clean the hoop with hot water, dry, and store back in the crate.

Post processing

Bioplastics can be lasercut, sewn (when using a sewing machine, transport goes better when you attach some thin paper under and on your material), remelted over an object with a heat gun, silkscreened on, used as glue... just experiment, don't forget to document your process, and get to know the material!

!! This was a quick and simple starting guide. Feel free to explore all the other recipes and cook books available on the other pages, or sign up for our in-depth biomaterial course. Have fun!