CHARCOAL BIOLEATHER

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GENERAL INFORMATION

This material was inspired by the Restology Project that developed a series of biomaterials containing activated charcoal as a possible solution for air pollution in the city of Monterrey, Mexico.

“Activated charcoal is one material that seems especially applicable to Fab Lab makers, because of its ecologically sound and purifying properties. It is essentially a form of incredibly microporous carbon, processed from natural carbon-rich materials by applying various gases or chemicals to ‘burn’ in tiny holes and thus exponentially increasing its surface area. The result ? A material that can efficiently filter out all manner of impurities and toxins. A super-sponge, if you will. Bioplastics present themselves as an excellent and similarly sustainable substrate for activated charcoal with a wide range of uses” Clara Davis on Restology

Using one of the recipes as a starting point, some adjustments were made and the final material had a very different appearance than the other gelatine bioplastics. Is completely matte and has a less “silicone” like texture, so it becomes closer to leather fabric than to plastic. This material also has the same air filtering properties as the ones from Restology project (yet to be tested), having the potential to act as an air purifier.

This recipe template was developped by Loes Bogers, as a part of her final project in Fabricademy 2019/2020.

Physical form

Solids

Color without additives: Black

Fabrication time

Preparation time: 2 Hours (time really depends on the recipe’s total amount)

Processing time: 7 days

Need attention: every 12 hours, check if it’s drying properly, not molding or bending.

Final form achieved after: 10 days

Yield

Approx. 1200 ml.

I usually assume that 20% of the water evaporates during the cooking time, but this really changes based on how much stirring or how long you leave the mixture on the heat. The longer you simmer, the more water will evaporate, which means less shrinkage during the drying process.

Estimated cost (consumables)

TBA

RECIPE

Ingredients

  • Gelatine Powder
    • Amount: 300 gr
    • Functions as the polymeer (so it becomes a solid)
  • Glycerine
    • Amount: 300 gr
    • Functions as plasticizer that bonds with the gelatine (makes it flexible).
  • Water
    • Amount: 1200 ml/gr
    • To dissolve and mix the polymer and plasticizer
  • Activated Charcoal - powder
    • Amount: 90 gr
    • Is a filler, it helps on shrinkage and also adds a porous surface to final material
  • RATIO
    • Gelatine / Glycerine = 1
    • Water / Gelatine = 0,25

Tools

  1. Cooker or stove
    • Is this tool optional? No
  2. Pot & Spoon
    • Is this tool optional? No
  3. Scale
    • Is this tool optional? No
  4. Casting Sheet
    • Is this tool optional? No
    • I used bacrylic and glass as a casting surface, with a border made of acrylic stripes of 3mm. The acrylic thickness should be higher than 5mm to avoid bending while casting.
  5. Kitchen Grinder
    • Is this tool optional? No (unless you purchase the activated charcoal in powder)

Method

  1. Preparation

    • Weigh your ingredients
    • Grind the activated charcoal until is very thin
    • Clean the sheet where you are casting and find a place where you can leave it for a while, ideally near an open window where there's air flow

  2. Mixing and dissolving the ingredients

    • Bring the water to the stove
    • Add the gelatine, wait for it to dissolve completely
    • Add the glycerine
    • Add the activated charcoal

  3. Cooking the ingredients

    • Simmer and slowly stir the mixture between 60-80 degrees celsius for 50-60 minutes, until it's like a syrup
    • Bubbles and foam: the bigger the recipe the more foam you will get, for this recipe I really liked the final look the foam gives, a greyish cool pattern. However if you are willing to make a full black sheet, removing the foam is needed. After simmering for about 20 minutes you can start removing the foam, with the help of a big spoon or with a (not so sustainable but very effective) plastic bag method. It consists in getting a piece of plastic (I used some leftover from food packaging) and gently let it touch the upper surface of your mixture, remove it in seconds and you will see that most of the foam is glued to your plastic.
    • Longer cooking time allows more water to evaporate and as a result it will shrink less during drying. Make sure it's still liquid enough to pour

  4. Casting

    • When casting big sheets, you need to be somehow fast in pouring the mixture in order to make sure you are covering all the surface and maybe some places will require you to drag the liquid into, you can do that with a wooden stick or a squeegee. Maybe some air bubbles will come out, while the liquid is still hot, you can pop these bubbles by just poking them with something sharp
    • With this recipe I had troubles casting because the acrylic sheet started bending due to the heat, this causes the material not to flow/ spread evenly throughout the sheet and accumulate in some areas, therefore thicker acrylic (> 5 mm) or glass is ideal
    • After about 30 minutes you can move the mold to dry in a cool place with lots of air flow (like near an open window). A warmer place might speed up the drying process but also allow bacteria to grow faster and can result in fungal growth. Avoid direct sunlight as the gelatine can also get more sticky

Drying/curing/growth process

  • Mold depth: 2 mm
  • Mold size: aprox 80 x 50 cm
  • Shrinkage thickness: 20% (after dry material thickness was between 1-1,8 mm)
  • Shrinkage width/length: 5% (after dry the sheet had 76 x 47,5 cm)

Shrinkage and deformation control

Letting it dry up to ten days to get to the final form. It will be very flexible at first but will slowly harden. The longer in the mold, less deformation the final material will have.

When casting on acrylic surfaces the material can be easily peeled off even when totally dry. However casting on glass can be harder to remove, specially if the final thickness is less than 1mm, in this case I recommend peeling off the material after 2 or 3 days drying and then leave it to dry on top of baking paper.

Curing agents and release agents

None.

Minimum wait time before releasing from mold

3 days (but also depends on the thickness of the material, thinner will take less time to dry)

Post-processing

Store in a dry and ventilated room. If you need to move the sheet around, I suggest to place baking paper on both sides and roll it.

Further research needed on drying/curing/growth?

The material itself has proven to be very resistant, flexible and durable when stored in dry and mild temperature places.

In smaller sheets I have tested rubbing beeswax on the surface, it makes it matte but very waterproof. There is still room for development on how to do this effectively, but I believe to be an excellent solution for the water sensitivity of this material.

Process pictures

Activated charcoal in powder, Beatriz Sandini, 2020

Charcoal Bioleather sheet casted, Beatriz Sandini, 2020

Adding the charcoal and after 60 minutes the texture and consistency before casting, Beatriz Sandini, 2020

Variations

Add first experiments

ORIGINS & REFERENCES

Cultural origins of this recipe

Bioplastic production is older than petroleum-based plastics. In 1500 BC, people in Egypt were already using glues based on gelatin, casein and albumin for furniture constructions. Gelatin casting as a technique has also been used in production of jelly-based foods such as aspic, jelly desserts and candy. Plastics are man-made polymers that can be produced with petrol-based compounds but also biomass. The process to create them is called polymerization, or the chemical reaction to form polymer chains or networks. In 1862 Alexander Parkes presented Parkesine (now celluloid, an organic thermoformable material made from cellulose). In 1907, Bakelite was introduced by chemist Leo Hendrik Baekland. Bakelite is an electrical insulator and was used in electrical appliances, once formed, it could not be melted. Baekland coined the term "plastics" to describe a new category of materials. PVC (short for polyvinyl chloride was patented in 1914 (around the same time cellophane was discovered). The use of petroleum was easier and cheaper to obtain and process than raw materials like wood, glass and metal and gained in popularity after World War II. More plastics were invented and became mainstream in the 1960s thanks to its ease and low cost of production. High tech plastics continued to be developed for health care and technology since the 1970s. In short: not all plastics are petrol-based. Henry Ford experimented with plastics made from soya beans as early as 1941. Common plastics like celluloid and PLA - are also biobased but are not necessarily better in terms of reducing pollution: The time and conditions they require to decompose and be reabsorbed in nature are crucial in determining how sustainable plastics are. On open-source bioplastics: open-source documenting of how to make bioplastics with simple tools and locally available materials can be attributed to Miriam Ribul and her publication on Material Activism from 2014. Promoting collaborative production of alternatives for petroleum-based plastic, she demonstrated 20(!) known processes for material production using only 4 simple recipes. Juliette Pépin's visual research book on bioplastics (also from 2014), goes in depth into the sensory and visual aspects of simple recipes with many variations. Although bioplastics production is certainly a craft that is dispersed across many locations and times, leaving traces of many similar recipes behind, this type of cataloguing and sharing work is certainly indebted to these two pioneers.

This section is attributed to Loes research and documentation

Needs further research?

Further research on the end of life cycle is needed. Better understand the timing and ideal conditions for composting.

Key Sources

Biosilicone Recipe by Cecilia Raspanti (TextileLab, Waag), Fabricademy Class "Biofabricating Materials", 2017-2019, link.

Recipes are published under a CC Attribution Non-commercial licence.

ETHICS & SUSTAINABILITY

Needs further research.

Gelatin is an animal-based ingredient. Some might find it problematic to use resources that require killing an animal because of religious or animal welfare beliefs. Arguments are also made that as long as there's a meat industry, it is better to use product from the entire animal, including skin and bones. Some might consider gelatin to be a product that comes from a waste stream, but this is considered controversial by others. Acrylic (for the mold) is a petroleum based plastic but results in very shiny foils and sheets and can be reused endlessly for casting high quality bioplastic sheets. Using renewable ingredients is not by definition petrol-free. Imagine they have to travel long distances by plane, boat or truck: it takes fuel. Also, the effects of GMO technologies and pesticides can be harmful to the environment and it's worth using knowing the source and production standards involved. If you can afford it, buying organic ingredients is a good starting point.

This section is attributed to Loes research and documentation

Sustainability tags

  • Renewable: yes
  • Vegan: no
  • Made of by-products or waste: no
  • Biocompostable: yes, ideally in a home composting bin. Timing still to be further understood.
  • Re-usable: yes, by melting and recasting

Needs further research?: Yes, on activated charcoal

Gelatine-based bioplastics can be recasted by melting them in a pot with some water (but plastics with additives and fillers might not be reusable). Should not be recycled as part of PET-plastics waste: this causes contamination of the waste stream. Compost bioplastics in a warm environment with sufficient airflow.

PROPERTIES

  • Strength: strong
  • Hardness: flexible
  • Transparency: opaque
  • Glossiness: matt
  • Weight: medium/heavy
  • Structure: closed
  • Texture: smooth
  • Temperature: cool
  • Shape memory: medium
  • Odor: moderate in final form, strong during production. While cooking I classified the smell as “puppy pee”. When laser cutting, it also stinks a lot, it takes some weeks for the burnt smell to go away.
  • Stickiness: medium
  • Weather resistance: poor
  • Acoustic properties: needs further research
  • Anti-bacterial: needs further research
  • Non-allergenic: needs further research
  • Electrical properties: needs further research, but has the potential to be conductive material
  • Heat resistance: low
  • Water resistance: low
  • Chemical resistance: needs further research
  • Scratch resistance: moderate/high
  • Surface friction: sliding/medium/braking/variable
  • Color modifiers: none

ABOUT

Maker(s) of this sample

  • Name: Beatriz Sandini
  • Affiliation: Fabricademy student at Waag Textile Lab Amsterdam
  • Location: Amsterdam, the Netherlands
  • Date: 20-01-2020 – 01-03-2020

Environmental conditions

Outside temp: 5-11 degrees Celsius Room temp: 18 – 22 degrees Celsius PH tap water: 7-8

Recipe validation

Has the recipe been validated? Yes, by

Images of the final sample, variations & final product

charcoal

REFERENCES

  • Restology by Yessica Mendez Sierra et all (Centro de Estudios Superiores de Diseno de Monterrey S.C.), 2017, via issuu link
  • Biosilicone Recipe by Cecilia Raspanti (TextileLab, Waag), Fabricademy Class "Biofabricating Materials", 2017-2019, link
  • The Secrets of Bioplastic by Clara Davis (Fabtex, IAAC, Fab Lab Barcelona), 2017, link
  • The Bioplastics Cookbook: A Catalogue of Bioplastics Recipes by Margaret Dunne for Fabtextiles, 2018, link
  • Recipes for Material Activism by Miriam Ribul, 2014, via issuu link
  • Polymerization, on Wikipedia, n.d.: link
  • Lifecycle of a Plastic Product by American Chemistry Council, n.d. link
  • Research Book Bioplastics by Juliette Pepin, 2014, via issuu link