7. BIOFABRICATING MATERIALS¶
INSPIRATION¶
- Agar bioplastic - NOT x LIENX
- Biocouture - Suzanne Lee
- Gelatine garment, 2021 - Valdís Steinarsdottir
- Mylo garments from vegan mushroom leather, 2021 - Stella McCartney
- Xiva Reishi Coat“ - MycoTex, Deadwood Studio
SELFMADE BIOMATERIALS¶
This week we worked with biomaterials trying out recipies with mainly agar, gelatine and alginate
Agar¶
For our self-made biomaterials project, our group experimented with a range of different substances. I focused on testing agar as a base for creating a flexible foil. I followed the recipe provided in the instructions but replaced water with an oak gall dye bath. Since oak galls contain a high concentration of tannins, they react strongly with iron. My idea was to create a biomaterial using the oak gall mixture and then partially blacken it by applying drops of iron onto the surface.
Because the agar mixture did not thicken as expected, I carried out another experiment by adding potato starch to the liquid to increase its stability and density. I cast the material onto an iridescent foil to transfer its shimmering surface to the biomaterial. Additionally, I tested casting it on a textured foil to create a relief effect.
The process worked fairly well, but since the agar layer was very thin, some parts ripped while being removed. The version with added starch was cast much thicker, but despite storing it in the hydrator, it developed mold after some time.
Alginate¶
Alginate differs from materials like agar or gelatin because it is processed cold. The main ingredients—alginate, glycerin, and water—are mixed together, and additives such as color pigments or texture-enhancing elements can be incorporated. The mixture should rest for about 24 hours to allow any air bubbles to escape. After casting, the material must be sprayed or covered with a 10% calcium chloride solution. This triggers a chemical reaction that alters the molecular structure, making the alginate water-resistant and able to withstand heat up to 150 degrees Celsius.
Alginate & Shells
For this experiment, I cast alginate onto a frame and embedded bird nutrition shells from a pet shop. The mixture consisted of 12 g alginate, 40 g glycerin, and 400 ml water, with ochre pigment added for coloring.
Drawing with Alginate
With the same recipie it put it in a bottle with three openeings and draw a pattern on a denim fabrics.
Alginate Foam We also experimented with creating alginate foam. Using the same base recipe, we added dishwashing soap to the mixture and stirred it vigorously. The result was a soft, velvety foam with a delicate texture due to its thinness.
Alginate & Cat tails
This version used 12g alginate, 40 g glycerin and 400 ml of a cochineal dye bath to achieve a vibrant red tone. I incorporated cattails for additional structure, as their fibrous composition was intended to improve the stability of the material.
Algae Yarns
For the algae-based yarns, we filled the prepared alginate mixture into a bottle and allowed it to rest for 24 hours. We then extruded it directly into the calcium chloride solution, initiating immediate solidification. After rinsing the yarns with water, we shaped them around a jar to control shrinkage—ensuring they contracted in height but retained their length.
Casein¶
We experimented with making biomaterial from casein, since milk production often leaves behind leftovers unsuitable for consumption. We tried both 0% fat (skim) milk and milk with 1–2% fat.
Using skim milk worked better for our purpose. The process started by pouring milk into a jar (using 0% fat milk), then adding vinegar to acidify the milk. Shaking the mixture causes the casein to precipitate out, separating from the liquid. This acidification extracts the casein effectively. We rised the casein through a dense woven fabric and dried it afterwards. The casein powder can be used as pure biopolymer or mixed with other biopolyemrs as agar.
For the milk with 1–2% fat, we used a different approach inspired by Marieke Eindhoven: we added soda bicarbonate to raise the pH to about 10, which helps extract the fat. After letting the mixture stand, we then acidified it with vinegar to lower the pH to around 4.6, causing the casein to coagulate and separate.
I'm curious to work with the casein powder at another occasion.
GROWING MATERIALS¶
Kombucha leather¶
We set up two different batches with kombucha—one with green tea as described in the following recipe, and the other mixing in rose petals to create a more colorful version. We actually wanted to use hibiscus, but since we only had rose petals, we used those as an experiment.
Ingredients (for 1 liter)¶
- About 200 ml unpasteurized kombucha starter plus a SCOBY
- 1 liter black or green tea
- 50–60g sugar
- Apple cider vinegar to adjust pH to ~5, if necessary
- Ferment at 25–30°C, outside direct sunlight
1. Prepare Sweet Tea
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Boil the water, dissolve the sugar (50–60g per liter), and steep the tea.
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Remove the tea leaves once it’s steeped to prevent mold from forming.
2. Add Kombucha
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When the tea cools to below 30°C, pour into a clean container.
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Add the kombucha starter and SCOBY.
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Use apple cider vinegar to reduce the pH to about 5, if needed.
3. Fermentation
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Cover the container with a cloth and secure it to allow airflow but keep out dust.
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Let ferment at 25–30°C, out of direct sunlight, for 2–3 weeks.
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A thick SCOBY (cellulose sheet) will develop on the surface.
4. Harvest and Dry
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Remove the SCOBY gently—this is your raw “leather.”
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Rinse it well in cold water to clean off any residue.
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Lay it flat on a smooth, clean surface and let it dry for up to a week (depending on thickness and humidity).
5. Treatment for Flexibility
- Once dry, the material can be brittle. Rub with glycerin or linseed oil (optionally mixed with melted beeswax) to rehydrate and make it flexible and waterproof.
Tips
- The growth rate and thickness of the SCOBY depend on sugar, tea concentration, temperature, and fermentation time.
- Drying at a thickness of 8–15 mm gives the best leather-like results.
- The finished kombucha leather is compostable and can be cut, sewn, or molded as desired.
- Since the kombucha needs to grow for about three weeks, there’s no result yet.
Mycelium¶
We worked with oyster mushroom mycelium. Our process began with a pre-cultivated bag of mycelium. We ensured that our workspace was as clean as possible to minimize contamination risks. First, we opened the bag of cultivated mycelium and gently broke it into smaller pieces. Then we moved to the sterile workstation, where constant airflow helps keep bacteria out by preventing stagnant air.
We prepared hemp fabric that had been sterilized through autoclaving, making sure it was completely clean and free of contaminants. In the sterile workstation, we laid out the hemp fabric and carefully placed pieces of the mycelium on top, dispersing them evenly across the surface. Once the fabric was inoculated, we wrapped it in foil to protect it from bacteria and other contaminants, but added a few small holes to ensure it could breathe.
The goal was to encourage the mycelium to colonize and grow throughout the hemp fabric, forming a cohesive structure as it develops. There is also another method for growing mycelium using liquid cultures, which can allow faster growth or larger yields, but since we were short on time, we didn’t pursue this option.
FUR & FISH SKIN¶
Vegan Fur from Cattails¶
We made natural fur material using cattails collected from a canal near the textile lab. We focused on the brown flower heads of the plants, as inside these cat tails is a soft, furry layer that we wanted to use as fur.
Process for Making Cat Tail Fur
- Collect and prepare material
- Collect brown parts of cattails from the canal.
- Cut out a fabric piece larger than the length of the cat tail, enough to wrap around the plant (e.g., 17" long and 9" wide).
- Cover the cattails
- Cover the cattails with glue to ensure the fur layer sticks.
- Roll the fabric tightly around each cat tail, forming a sausage shape. Making sure the glue adheres well.
- Dry the rolled cattails
- Place the rolled-up cat tails in a dehydrator or dry them thoroughly until completely dry.
- Proper drying ensures the glue bonds and the fur layer stays attached after opening it up.
- Cut and open the fur
- Once dry, make a single cut lengthwise along the surface, cutting through the fabric and the brown layer of the cat tail.
- Gently massage the rolled tail to soften it and carefully open the slit to revealing the furry interior of the cat tail. Be gentle when opening the slit to preserve the fur layer.
Tipps
- Older, brown-stemmed cat tails yield better results, as the fur layer stays complete without any holes. The fresh, green stems tend to stick too. much on the fur, making it harder to open and damaging it at some parts.
Fish Skin¶
Having worked extensively with various biomaterials, I found fish skin particularly exciting to try. Although it is an animal product, I was comfortable working with it since it's typically a waste product. We went to a fish store and asked for leftover salmon skins, and luckily, we received quite a lot.
The first step was cleaning the fish skins. Although the skins looked quite clean initially, I learned they must be completely free of any flesh and the greasy layer beneath it. Using a spoon, we carefully scraped the flesh off in one smooth motion from head to tail, applying firm pressure. At first, I was worried about damaging the skin, but it turned out to be very strong—without enough pressure, it wouldn't come clean. After the flesh was removed, we flipped the skin and gently scraped off the scales from tail to head (opposite the scale direction), being careful not to damage the skin. Cleaning one skin took about 20–30 minutes.
After thorough cleaning, we washed the skins multiple times with soap and water until they looked clean and the fishy smell was reduced significantly. A useful tip is to wear gloves, or else the smell lingers on your hands.
Next, we massaged the skins to make them more elastic. Wanting to experiment with different treatments, we split the skins into two batches:
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Tannined with Ethanol and Glycerin
We mixed 500 ml glycerin and 500 ml ethanol in a jar, stirred well, and submerged the skins. They stayed in the jar for three days, shaken vigorously every few hours (kindly done by Flora). The ethanol makes the skin more transparent and facilitates easier coloring.
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Tannined with Egg Yolk and Oil
For the second batch, we whisked two egg yolks with some oil and a bit of water. We soaked the skins in this solution for half an hour, then massaged them with it for another half hour to ensure deep absorption. After soaking, we wrung the skins out and hung them to dry. Before drying, we massaged them again to improve elasticity. Ideally, the skins should be massaged throughout the drying process, but since it was the weekend and we couldn’t access the building, we left them undisturbed.
After the weekend, the skins were dry but very stiff. We plan to wet and massage them again, then pin them to wood to dry smoothly and regain flexibility.
