Bioplastics are biodegradable plastics whose components are deriveD entirely or almost entirely from renewable raw materials.
Bioplastics are composed of three basic parts: one or more polymers, one or more plasticizers, plus one or more additives.
Polymers give the plastic its strength, plasticizers give it its bendable and mouldable qualities, and additives give it other properties (color, durability, etc). (Green Plastics)
Biopolymers: agar, Psyllium ovata, gelatin,
Additives: ground coffee, natural dyes, ground eggshell, dried flower leaves,
All above tests are made by me at the Iaac Fab Lab Barcelona. We used 2 recipies witht the same ingredients but with a variety in quantities.
General principle: The more glycerine or glycerol, the more the bioplastic will be flexible, but less strong. Less glycerine is stronger bioplastic but more rigid.
The material made with the basic recipe starts to harden rather fast. Adding vinegar and/or coffee ground makes it thicker. Too much glycerine gives it a very jelly look. The support on which it dries is important for the finishing touch. Drying on paper trays gives a nice mat shade, while drying in plastic trays gives it a very slick and neat finishing.
The samples we made with little glycerine are hardening out fast. The gelatin gives a very clear look once the sheets harden out in a thin layer.
We made samples with hemp fibers in it - to make it stronger but still flexible. We also did tests adding platics bubbles and fabrics. It is also possible to cast objects in a thicker layer of bioplastic, acting as natural resin or epoxy, see the voronoi example (below).
In a second batch (see darker brown samples in pictures above) I experimented with the basic recipe + grounded coffee (2 tbs and 4 tbs). I might use less glycerol for that recipe, the substance was too jelly. I made also some samples wih Psyllium (or a surrogate: Plantaben). I had to add much much more water than prescripted, the result is a thick gravy and probably it will take a few days before the water will evaporate. But the first results are absolutely promising, if the layers are cast thin enough. After a few days the sheets dry out very hard. I should find a good mix of ingredients (more glycerol?) to keep them a bit more flexible.
When I came back from Berlin after a few days, the samples with the Psyllium-mix (the ones where I had to add a lot of water) were full of mold. Same for the thick casted samples with gelatin and coffee ground. The samples that were casted in a finer sheet were all OK.
In a third batch (started in Berlin, early May 2016) I experimented with Agar vs. Gelatine. The Agard works quite well, but the film is ultra thin and very fragile. I should make a new Agar-test with a thicker layer to check out the materials' comportment.
The test with gelatine hardens out fast but takes up to 2 à 3 days to dry completely. I experimented with the basic recipe and added brewed coffee liquid, ground coffee (used) and crushed eggshells. I casted the 3 experiments in a similar plexi container, and on a similar thickness (±8mm when liquid). The exp. with ground coffee has the thickest substance, and after 2 days (still not hard) shows a burst in the surface. The brewed coffee exp. (in 2 large containers) gives no problem, and in the crushed eggshell exp. the grains of eggshell sink to the bottom of the container, which makes that the top of the cast is caramel-brownish, and the bottom is broken-white. I am curious to see the result when the material will be completely hardened.
engraving with the laser cutter
the basic ingredients:
Glycerol, glycerine or sorbitol
Agar, gelatin or starch (classikool.com for gelatine)
(adding agar makes the bioplastic longer lasting and is good against britleness)
Dusting with babypowder prevents stickyness
Handy to work with a readymade 1% glycerol solution
Releaser: teflon spray, vaseline
Adding a bit of wax can make the material more hydrophobic (as normally bioplastics will dilude with water)
Some drops of essential oil can be added to prevent from molding.
the basic recipe:
240 ml of water or 20tbs water + 10tbs black coffee
48 g of gelatin powder or 4 tbs gelatin powder
12 g of glycerol (ev. less glycerol) or 1tbs glycerol
quantities can be adjusted but ratio is 20:4:1
add 12g of vinegar to make the mixture stronger (not necessary)
grounded coffee or other extras can be added - make a thicker mass.
the alternative recipe (for thin sheets):
6gr of gelatin
3,2g of glycerol
160ml of water
3.0 g agar (2g agar)
240 ml of 1% glycerol solution (160ml glycerol solution)
180 ml water (120ml water)
2.25 g sorbitol
2.25 g gelatin
2.25 g agar
180 ml of 1% glycerol solution
240 ml (1 cup) water
3,5 gr plantaben
2 tbs vinegar
1 tbs glycerol
Cast objects into the bioplastic
Add coffee ground, crushed eggshells, orange peel to the basic recipe
lamination in the vacuum machine:
Add several thin layers of still flexible bioplastic sheets
Put them accross each other on/in the mold