biosilicon.md



BIOSILICONE

Tactility & sound impression


Description
A (naturally) yellow, flexible biosilicone, gelatin-based.

Physical form
Solids
Color without additives: transparent, yellow

Fabrication time
Preparation time: 1 Hour
Processing time: 5-10 days
Need attention: every 12 hours, alternate pressing and drying, (press overnight, let dry through the day for example, or leave to dry on a roster). Leave it to dry as long as is feasible with lots of airflow.
Final form achieved after: 10 days

Ingredients


Gelatine powder - 48 gr

Functions as the polymeer (so it becomes a solid)


Glycerine - 48 gr

Functions as plasticizer that bonds with the gelatine (makes it flexible).


Water - 240 ml/gr

To dissolve and mix the polymeer and plasticizer


Tools


Cooker or stove (optional: temperature controlled)
Pot
Scale

Moulds (I use a modular mold from laser cut 3 mm acrylic sheets here that are held together with screws)
Spoon


Yield before processing/drying/curing
Approx. 250 ml (make sure to evaporate enough water during cooking time)

Method


Preparation

Weigh your ingredients
Prepare the mold and find a place where you can leave it for a while, ideally near an open window where there's air flow.


Mixing and dissolving the ingredients

bring the water to the boil
optional: add natural dye if you wish to use color
add the glycerine
add the gelatine
keep the temperature below 80 degrees celcius while stirring very very slowly and gently to avoid making bubbles. I prefer a simple spoon to do this, not a whisk.


Cooking the ingredients

Simmer and slowly stir the mixture between 60-80 degrees celcius for 20-25 minutes, until it's like a syrup.
Longer cooking time allows more water to evaporate and as a result it will shrink less during drying. Make sure it's still liquid enought to pour.


Casting

Cast into the mould slowly to avoid bubbles
Pour from the middle and hold still, let the liquid distribute itself.
Put the mould away 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.


Drying/curing/growth process

Mold depth:  				3 x 3mm layers
Shrinkage thickness:      20-30 %
Shrinkage width/length:   10-20 %

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. Tends to curl up if it is not pressed down during drying (the design of this mold allows for airflow even when pressed). Laying it on a smooth surface helps to keep it flat, it "sucks" onto the surface.
Curing agents and release agents
None.
Minimum wait time before releasing from mold
3 days
Post-processing
Store in a dry and ventilated room.
Further research needed on drying/curing/growth?
Casting larger volumes without growing fungus/mold and deformation would require further experimentation.

Process
preparing the mold, Loes Bogers, 2020
thick mixture, Loes Bogers, 2020
biosilicone slab just after mold release, Loes Bogers, 2020

Variations on this recipe

Add a natural colorant such as a vegetable dye or water-based ink (e.g. hibiscus, beetroot, madder)
Add less glycerine for a rigid biosilicone

Stiffeners such as fibres, yarn or natural debris may be added for more structure and reinforcement.

Fillers such as almond or sunflower oil, can be added to prevent additional shrinkage but might affect stickyness.


Cultural origins of this recipe
Bioplastic production is older than petrol 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.
Needs further research?   Not sure

References this recipe draws from


Biosilicone Recipe by Cecilia Raspanti (Textile Lab, Waag), Fabricademy Class "Biofabricating", 2019, link.


Known concerns and contestations*
Needs further research
Gelatin is an animal-based ingredient. Some might find it problematic to use resources that requires 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 petrol 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.

Sustainability tags

Renewable ingredients: yes
Vegan: no
Made of by-products or waste:  no
Biocompostable final product:  yes
Reuse: yes, by melting and recasting

Needs further research?:  not sure
Gelatine-based bioplastics can be recasted by melting them in a pot with some water. Recycling them with PET plastics contaminates the waste stream. Compost bioplastics in a warm environment with sufficient airflow.

Material properties

Comparative qualities
This silicon is rather flexible considering it's thickness, but is quite hard when compared to silicone rubber baking trays for example that often contain softeners. Thinner sheets are more flexbile, thicker less.

Technical and sensory properties


Strength: strong

Hardness: flexible

Transparency: transparent

Glossiness: glossy

Weight: medium

Structure: closed

Texture: smooth

Temperature: medium

Shape memory: high

Odor: moderate in final form, strong during production

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

Heat resistance: low

Water resistance: water resistant

Chemical resistance: low

Scratch resistance: high

Surface friction: braking

Color modifiers: none


About this entry

Maker(s) of this sample

Name: Loes Bogers
Affiliation: Fabricademy student at Waag Textile Lab Amsterdam
Location:  Rotterdam, the Netherlands
Date: 19-02-2020 – 01-03-2020


Environmental conditions

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


Recipe validation
Has recipe been validated? Yes
By Cecilia Raspanti, Textile Lab, Waag Amsterdam, 9 March 2020

Estimated cost (consumables) in local currency
1,68 Euros for a yield of approx 300 ml

Local supplier/sourcing info
Gelatin powder - Jacob Hooy (online retailers)
Glycerine 1.23 - Orphi/Chempropack (online retailers)
Molds - acrylic sheet from hardware store or online retailers, lasercut
Nuts and bolts - from hardware store

Copyright information

This recipe is in the public domain (CC0)
Yes

This recipe was previously published by someone else
Yes, in: Biosilicone Recipe by Cecilia Raspanti (Textile Lab, Waag), Fabricademy Class "Biofabricating", 2019, link.
##References


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


Biosilicone Recipe by Cecilia Raspanti (Textile Lab, Waag), Fabricademy Class "Biofabricating", 2019, link.


Images of final product
Biosilicone sample, Loes Bogers, 2020
Biosilicone sample, Loes Bogers, 2020
Biosilicone sample, Loes Bogers, 2020
Biosilicone sample, Loes Bogers, 2020