Kombucha leather differs from traditional vegan leather because it is not synthetically based like plastic. It is instead biologically based, from bacteria and yeast. Due to its biodegradable nature, it’s great for shorter-life projects like wallets, shoes, clothing, costumes, and cosplay. For anything that doesn’t need to last decades, kombucha will do. As a bonus, at the end of the product’s lifecycle it can be thrown in the compost.
This kombucha textile begins with sweet tea, either black or green, and a bit of kombucha SCOBY (“Symbiotic Colony of Bacteria and Yeast”) added after the tea is cooled. The process takes about 2 weeks to form.
The textile is the result of the bacteria in the SCOBY creating a pellicle. The pellicle is the skin or film that’s formed by the SCOBY, allowing it to float and giving the aerobic bacteria access to consume oxygen (Figure A). The yeast in the SCOBY consumes the sugar and ferments the tea into the kombucha drink.
The pellicle is often referred to as bacterial cellulose in scientific papers and is the most pure form of cellulose on the planet. It is 100% biodegradable.
All in the Name: Kombucha, the refreshing fizzy fermented tea beverage, shares the same name with the kombucha that can be used for truly vegan ecofriendly leather. Kombucha in this article refers to that very leather.
A few simple ingredients are needed for brewing kombucha. This recipe can be multiplied. I typically brew 4 to 8 gallons at a time depending on my project.
- 1 gallon water
- 1 cup of sugar White or table sugar is ideal, but feel free to experiment with brown sugars and pasteurized honey.
- ½ ounce of loose leaf tea, black or black/green blend or 6–7 black tea bags
- ½ cup of starter kombucha i.e. already brewed kombucha
- 1–2 small pieces of SCOBY, or 2 bottles of kombucha Time and results are the same.
A few simple tools are needed for production:
- Stovetop or other way to brew a minimum of 1 gallon of tea at a time
- Large pot and spoon to brew sweet tea
- Container(s) for growing kombucha, ideally plastic or glass
- Container to keep your mother SCOBY happy, ideally glass
Note that kombucha SCOBY will grow in the shape of its container, no matter the profile: circular, square, etc. I used under-the-bed storage containers that are about 32″×12″ for growing large sheets. I brew enough for two to four containers at a time and fill these containers with 2 gallons of sweet tea each.
1. Bring the water to a boil and dissolve the sugar.
2. Turn off the stove and add the tea (Figure B). Let it steep for 15 minutes, minimum. You can also brew it in the evening and let it cool, covered, overnight. Remove the tea bags or loose leaf tea after steeping.
3. Once the tea is room temperature, add it to the brewing container (Figure C). This can be glass or plastic. Make sure there is 4”–5″ of sweet tea in the container for growing kombucha sheets.
4. Add the starter kombucha and 1–2 pieces of SCOBY, or two bottles of bottled kombucha.
5. Cover the container with a thin sheet of fabric and rubber band, and/or loose lid (fruit flies love kombucha and the fabric or lid will keep them from the tea). Make sure there is some air flow to the kombucha; don’t seal a lid shut on the container.
6. Leave the kombucha undisturbed in a dark, warm space for optimal growth. To expedite growth, keep the container in an 80°F–95°F environment. This will yield about ½” sheet of kombucha in 2 weeks. The pellicle will also grow in a cooler environment, but it will take longer to grow a viable thickness.
7. Once the kombucha pellicle is about ½” thick, it is time to harvest (Figure D)!
Drying It Out
The drying process can take as long as the growing process, but it requires more handling. The drying time will depend on the environment, temperature and humidity, and the quantity of layers desired. There will be considerable shrinkage in the thickness of the pellicle as it dries. Expect up to 90% of its thickness to be lost to evaporation.
No matter what your desired result is, the most important thing is to layer multiple sheets of kombucha as it dries (Figure E) — this will increase its strength and flexibility.
When a sheet of kombucha SCOBY dries, the nano-crystalline structure of its cellulose will align in a single direction. Each sheet will align independently, even if fused with other sheets. Layering these nano-crystalline structures in multiple directions by fusing multiple sheets increases the strength of the leather and reduces the chance of tearing and cracking when dried.
Sheets can be layered while wet, or a wet sheet can be added to a dry or almost dry sheet. This is how kombucha sheets fuse. One sheet can be grown at a time. A second sheet can be growing while the first sheet is drying. The fusing result will be the same whether fused wet-to-wet or wet-to-dry, the only difference will be the time. It’s faster to allow the first sheet to dry most of the way before adding the next layer.
Plan a minimum of four layers of kombucha to create a truly viable piece of vegan leather. This way its strength and flexibility will be increased as well as its dry thickness. You should also plan for some shrinkage in the length and height as the kombucha dries, but with daily massaging (Figure F) this will be minimal.
You can dry kombucha on a wet mold to create a three-dimensional shape (Figure G), or flat like traditional textile sheets (Figure H). The kombucha will pick up the small details of the surface that is dries upon. This makes creating an embossed sheet or form almost effortless.
Apply a thin layer of olive oil on the drying surface (either a mold or a flat plastic sheet) to prevent the kombucha from sticking when dried (Figure I). Olive oil will also make removal a breeze.
Remember to massage the kombucha sheets daily for a smooth, even texture when dried. If no massaging is done during the drying process the dried piece of kombucha will prune like a raisin and resemble wrinkly skin. Experiment with massaging levels to create different textures.
Working With Dried Sheets
Once dry, kombucha will behave much like leather. It can be cut, stitched, glued, painted, and dyed. It cuts easily with scissors in any direction and will not fray. Do be mindful that the scissors are stainless steel and that the kombucha is fully dry. If not, the scissors may rust.
Kombucha can be sewn beautifully by machine or by hand, just the same as leather. Use a leather needle, Teflon or walking foot, and a longer stitch length (4–6) when using the sewing machine. Again, work with fully dried kombucha when sewing. Otherwise the feed dogs and/or bobbin casing can rust. A leather punch can be used to create the holes for hand stitching.
Kombucha has this incredible ability to “heal” by fusing wet pieces over dry or almost dry sheets. The kombucha product is easy to repair if any tears, cracks, or holes occur. Figures J and K show a cracked piece before and after repair.
This ability also lends itself to attaching two or more pieces together. Seams can be fused. This is the ideal method if the desire is a 100% biodegradable product, but it also takes the longest time to complete. If there is a need for haste, rubber or contact cement can be used at the seams (this portion will need to be cut away before adding the rest of the kombucha product to the compost heap).
Each sheet of kombucha is likely to have imperfections like thin spots or holes where gas was released during the fermentation process. This can be solved two ways: either by patching the holes with other pieces of kombucha, or by creating sheets of blended kombucha.
There is evidence that blended sheets of kombucha can still dry with their nano-crystalline structures aligning in a single direction. So an imperfect sheet of kombucha can be harvested, blended into tiny pieces, and laid out in a sheet to dry. Once the first blended sheet is almost dry, you can add the next blended layer on top, or make a sandwich of full sheets and blended layers combined. Feel free to experiment to create the ideal textile for your desired project.
Dyeing and Painting
Being the most pure form of cellulose, kombucha is an ideal candidate for dyeing. It can be dyed when first harvested or after it is dried. When considering the weight for dye quantity calculations, use the weight of a dry sheet of kombucha. (Remember, the freshly harvested pellicles are mostly water.) Using natural dyes (Figures L and M) will create a stiffer sheet of kombucha when dry, while a fiber reactive (procion) dye will increase the flexibility of the sheet. Experiment with both to create the right color and texture for your kombucha product.
Paints and pigments can also be used to color the surface of the kombucha (Figure N). Cake paints work well and keeps the product fully biodegradable. Acrylic paints can also be used. Some increase in the material’s flexibility has been observed when using acrylics. As the kombucha ages, the paints darken in color. These can be touched up as needed.
Humidity levels will have a great impact on the life of the kombucha product. Lower humidity will lead to more stiffness, while higher humidity will increase flexibility. Use the techniques above to create a kombucha textile to suit your climate for the longest lifespan.
Kombucha resembles human skin when it dries without paint, pigment, or dye. Like human skin, it responds positively to lotions and oils. If traveling to a lower humidity climate, give it some lotion or body oil. Or use lotions to increase the shine. If cracks or tears do occur, heal it with a fresh piece of kombucha. The resulting patch can be sanded, once fully dry and fused, to create an even surface.
Kombucha may not be as durable as leather, but it can be completely composted at the end of its lifecycle. Kombucha vegan leather has a smaller environmental impact than PVC vinyl and actual leather. It is fun to grow right in your kitchen or on your back porch, and you can nurture a garden with it by adding it to the compost at the end of its use. Pretty neat, right?
This project appeared in Make: Volume 72.