ALGINATE FOIL¶

Tactility & sound impression¶

Description¶

An alginate based, heat-resistant and waterproof semi-transparent, matte foil

Physical form¶

Surfaces

Color without additives: semi-transparent, white when layered

Fabrication time¶

Preparation time: 1 hour (plus resting overnight)

Processing time: 5-7 days

Need attention: daily, to check if sheet needs to be taped down to stay in place on the mold

Final form achieved after: 7 days

Ingredients¶

Sodium alginate powder - 12 gr
- the polymeer (so it becomes a solid)
Glycerine - 20 gr
- the plasticizer that bonds with the alginate (makes it flexible).
Water - 400 ml/gr
- to dissolve and mix the polymeer and plasticizer
- optional: use a (diluted) natural dye instead for a colored plastic
Sunflower oil - 10 gr
- filler to reduce shrinkage
Calcium chloride solution 10% (10 gr to 100 gr water)
- is the curing agent: calcium chloride attracts moisture very strongly: spraying it onto the alginate plastic starts the curing process.

Tools¶

Scale
Spoon
Blender
Glass jar with lid
Spray bottle (150 ml contents, for the calcium chloride solution)
Acrylic sheet smooth surface to cast the foil onto. A smooth surface will create a smooth matte foil.
A strip of acrylic or squeeguee to push the alginate mixture into place and form an even and flat rectangle
Painting tape to tape down if edges of the sheet start to come off of the surface
Kitchen paper to soak up the water that will be released from the alginate mixture

Yield before processing/drying/curing¶

Approx. 200 ml of alginate plastic that can be stored for two weeks and used for any alginate application

Approx. 100 ml of calcium chloride 10% solution that can be used for any alginate recipe

Method¶

Preparation
- Weigh your ingredients for the alginate plastic (alginate, glycerine, water, sunflower oil). Optional: use a diluted natural dye instead of water in the same amount for a colored plastic.
- Put the oil, alginate and glycerine in a blender and add a dash of the water. Blend into a thick and homogenous paste. Then add the rest of the water and blend again (this is to avoid lumps).
- Leave the mixture overnight to allow the bubbles to come to the surface and pop.
- Make the calcium chloride solution by dissolving 10 gr in 100 gr hot water. Put it in a spray bottle.
Casting
- Prepare some space on an acrylic or glass surface
- Pour the alginate onto the acrylic sheet and use the squeeguee or acrylic strip to mold the liquid into a rectangular shape of about 3mm high
- Spray the sheet with the calcium chloride solution (use quite a lot)
- Let it sit for a few minutes, then spray again if you see the liquid is starting to ooze out from the sides. The film that is created in the curing process can break from the weight of the liquid bubble. By respraying you can close these until the sheet is cured enough and stable to dry further.
- The alginate can release quite a lot of water at this stage, so it's wise to place some kitchen paper around it to absorb excess water.

Drying/curing/growth process¶

Mold depth: N/A
Shrinkage thickness: 20-30 %
Shrinkage width/length: 10-20 %

Shrinkage and deformation control

Keep an eye on the sheet every few hours, especially on the first day. The thinner edges of the sheet might curl up when drying and pull of parts of the sheet. When it comes off it will start to warp. Taping it down onto the acrylic helps to keep it in place an dry in shape. Let it dry up to seven days to get to the final form. When it no longer feels cool to the touch it is dry enough to take off. If you want to trim the edges do it while the foil is still a bit softer for a clean cut.

Curing agents and release agents

Calcium chloride 10% as curing agent

Minimum wait time before releasing from mold

3 days but ideally a week

Post-processing

trim the edges with scissors or a scalper and ruler if you wish

Further research needed on drying/curing/growth?

Not sure

Process¶

Preparing the alginate the day before, Loes Bogers, 2020

The mixture is ready, Loes Bogers, 2020

Preparing a 10% calcium chloride solution with hot water, Loes Bogers, 2020

The calcium chloride solution in a spray bottle, Loes Bogers, 2020

alginate casted onto acrylic sheet, first few minutes of curing, Loes Bogers, 2020

Variations on this recipe¶

Replace the water with a (diluted) natural colorant such as a vegetable dye or water-based ink (e.g. hibiscus, beetroot, madder)
Add less glycerine for a less flexible foil
Take out the sunflower oil and use 30% less alginate to cast thinner foils
You can also use this recipe to make composites such as the one described in the alginate net recipe

Cultural origins of this recipe¶

Alginate plastic is used a lot in molecular gastronomy, for (reverse) spherification that was patented by William J. S. Peschardt in the 1940s and popularized in the molecular cuisine popularized by Adrian Ferra from restaurant El Bulli. Alginate plastics are also used a lot in molding and casting of dental technology industry.

Needs further research? Not sure

References this recipe draws from¶

The alginate recipe is a modified version of: Flexible Bio-plastic Alginate Recipe by Cecilia Raspanti (Textile Lab, Waag), Fabricademy Class "Biofabricating", 2019, link.

Known concerns and contestations*¶

Sodium alginate...... add text here

Sustainability tags¶

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

Needs further research?: not sure

Recycling this bioplastic with PET plastics contaminates the waste stream. Compost bioplastics in a warm environment with sufficient airflow.

Material properties¶

Comparative qualities¶

The foil has a feel that can be compared with a window foil (to blind windows but let the light through): it's matte but very translucent. It doesn't crackle or jump back like a lot of other foils.

Technical and sensory properties¶

Strength: medium
Hardness: flexible
Transparency: translucent
Glossiness: matt
Weight: light
Structure: closed
Texture: medium
Temperature: medium
Shape memory: medium
Odor: none
Stickiness: low
Weather resistance: needs further research
Acoustic properties: needs further research
Anti-bacterial: needs further research
Non-allergenic:needs further research
Electrical properties: needs further research
Heat resistance: high, up to 150 degrees celcius
Water resistance: waterproof (for PH neutral and acidic water, not for alkaline water)
Chemical resistance: needs further research
Scratch resistance: high
Surface friction: medium
Color modifiers: none

About this entry¶

Maker(s) of this sample¶

Name: Loes Bogers
Affiliation: Fabricademy student at Waag Textile Lab Amsterdam
Location: Amsterdam, the Netherlands
Date: 25-02-2020 – 02-03-2020

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¶

1,12 Euros for a yield for a sheet of alginate plastic (about a 50 cm x 12 cm sheet, 2 mm thick)

Copyright information¶

This recipe is in the public domain (CC0)¶

Yes

This recipe was previously published by someone else¶

This is a modified version of: Flexible Bio-plastic Alginate Recipe by Cecilia Raspanti (Textile Lab, Waag), Fabricademy Class "Biofabricating", 2019, link.

References¶

Flexible Bio-plastic Alginate Recipe by Cecilia Raspanti (Textile Lab, Waag), Fabricademy Class "Biofabricating", 2019, link.
The Science Of Spherification: Theoreticians examine the atomic details of an avant-garde culinary technique", by Bethany Halford, Chemical and Engineering News, Volume 92 Issue 42, pp. 35-36, October 2014: https://cen.acs.org/articles/92/i42/Science-Spherification.html

Images of final product¶

Alginate foil, Loes Bogers, 2020