This movie by designers Studio Swine demonstrates how waste plastic picked up by fishing trawlers can be transformed into chairs on board the boats.

Studio Swine first presented the idea in collaboration with Kieren Jones at the Royal College of Art show in 2011 and have since simplified the process to build the chairs using a small factory onboard vessels. They have released a manual so others can build the chairs too.

Plastic caught in fishing nets or found washed up on the shore is sorted according to colour and chopped into small bits, then melted at 130 degrees centigrade in a DIY furnace.

Some is then squashed between two flat slabs of heavy metal or stone to create the seat, while more is scraped into a mould formed from bent scraps of aluminium.

Cooled and solidified by the sea water, the seat and three legs are then scraped with a knife to tidy the edges and screwed together to create the Sea Chair.

Studio Swine have also designed a mobile food stall for cooking and selling pig heads and glasses made from human hair.

Scroll on for instructions for creating a Sea Chair from the studio:

Open Source Sea Chair by Studio Swine

Studio Swine has created an open source design based on 'Sea Chair' by Studio Swine & Kieren Jones, accompanied by a film of the process where a chair is made on a fishing boat at sea.

The United Nations estimates some 100 million tons of plastic waste to be contaminating in the worlds oceans, a proportion of which washes up on coastlines across the globe, last year Japan had over 200 thousand tons of plastic debris wash up along it's shores. This abundance of plastic presents an opportunity where the material is delivered by the sea to coasts where it can be processed to make new products with the intention of removing the plastic from the marine environment for good. The open source design uses readily available materials and basic DIY skills to enable the the creation of a sea chair.

You can download the Sea Chair manual here.

Things you need:

Furnace: a camping stove, a food tin, a steel kitchen pan with lid, a cooking thermometer, thick tin foil, glass fibre roofing insulation, crushed charcoal (for best results use perforated charcoal from an old water filter)

Moulds: a scrap aluminium L section (6cm x 6cm x 40cm approx.), two steel sheets (for best results polished stone off cuts from kitchen worktops, sink cut-outs or leftover floor tiles), Wax for mould release (beeswax or car polish)

Tools: a metal scraper, hacksaw, drill + metal bits, screw driver, three long screws, one or two small bolts & nuts

For Collecting: two buckets, kitchen or fine garden sieve, dustpan and brush, big bag, rubber gloves

The steps:

1. Collecting

Collecting plastic on the beach is the easiest way to get sea plastic; it prevents the washed up plastic returning to the sea to harm marine life.

Look at beaches during low tides where materials have been deposited, these are generally sandy beaches with debris along the strand line.

A dustpan and brush is effective for collecting small plastic pellets known as nurdles. These are often found deposited in lines below the main strand line of heavier materials such as seaweed. If the sand is flat and damp, then they can be swept off the surface without collecting the sand. Where sand is collected, they can easily be separated by sinking in a bucket of water and scooping out the floating plastic with a sieve.

Try to sort the plastic at this stage using the plastic chart, separate PET from LDPE, HDPE & PP which share similar melting points. Dispose of any PVC or Polystyrene collected. Small plastic pieces and nurdles are not possible to identify easily but if your averages are correct with the large items, the mix will work.

The plastic should all be broken up into pieces around 1cm x 1cm, this can be done by hand or a kitchen food processor. Add some water to the mix when using the processor to avoid the plastic from melting around the blades.

Remember: Dry the plastic before melting.

2. Melting

*Precautions*
Some essential precautions should be taken when melting plastic. Some plastics emit toxic fumes when melted. The lid and filter will help minimalise exposure to these, but also do any melting in a very well ventilated place away from others, outside if possible. Use a good mask and goggles to protect your eyes from smoke. Hot plastic will stick to the skin, so always wear thick gloves and long sleeves, leather gardening gloves are fine.

In the manual, there is a chart to identify plastics. However, chances are you won’t be able to easily identify a lot of the plastics you’ve collected. The key is to collect a sizeable amount of plastics of the same type so that they will mix well together when melted. It’s common to find large amounts of the same type of nurdles on a particular beach near where a spill once occurred, after you’ve identified the melting point they can form the majority of the mix that glues the rest together. Other beaches may contain mostly PET due to large amounts of discarded drinks bottles whilst some beaches contain a mix.

The majority of plastic waste is made of type1, 2, and 4 plastics. Wherever possible, avoid polystyrene and PVC, as they emit toxic fumes. The plastic pellets, or "nurdles", are all thermoplastics, which means they can me re-melted. Small plastic fragments found in the top layer of the ocean are most often HDPE, LDPE, and PP, as they are less dense than sea water and float, but, even if the plastic you find are thermosetting (which do not melt) they will still form an aggregate within the melted mass.

Once you have sorted your plastic and prepared it for use you can add them to the furnace.

Check the pan when the temperature reaches around 180ºC. If the mix is still hard, turn the heat up to 250ºC, checking at intervals to see when the mix is molten. As soon as the mix is molten enough to form a doughy ball in the pan when stirred, it is ready to use. Don’t worry if some of the plastic pieces aren’t fully melted, as long as the majority are, they will form a colourful aggregate within the material. Be careful not to leave the mixture too long, or the plastic will begin to burn and create more toxic smoke.

You need to decide whether your plastic mix is mostly Type 2, 4 & 5 or Type 1. In most cases it’s best to make a mix that mostly consists of Type 2, 4 & 5 which melt in the range of 110 - 170°C and use the Type 2 (melts at 250°C) as a aggregate.

If melting mainly Type 1 (PET) the plastics with a lower melting temperature can be added when the mix is molten and the stove turned off just before filling the moulds.

To make a stool, it’s recommended you heat around 3 batches of plastic separately, filling the pan each time about 1/3 full. Adding too much in one go will make it difficult to achieve an even temperature through the mix. An improvised windshield may be required for your furnace to reach higher temperatures.

3. Casting

Polish the leg mould with a cloth, and preheat the mould over the gas stove.

Use a metal scraper to scoop the plastic into the leg mould, overfilling them slightly. Press the full leg mould upside down against the flat surface used for seat mould. Press down on the mould until the metal sides are flat against the surface and the excess plastic squeezes out from either end. The excess should be cut off with the metal scraper and added back into the pot to be reused. Submerge the mould in cold water, this speeds up the curing process and makes the plastic contract away from the mould making it easy to remove.

When three legs are complete, a large blob can be melted to form the seat. Polished granite or marble kitchen worktop off cuts are the most effective surface for casting against, a sheet of smooth metal can be used as well, but it should be lubricated with oil or wax to avoid sticking to the plastic. Preheat the surface of the mould so the plastic stays in a molten state for pouring which will result in a smoother finish.

4. Assembling

Mark out an equilateral triangle on the base of the stool where the legs are positioned. Drill holes and screw in legs with screws approximately 3 inches long. If required, use some of the leftover melted plastic to weld the legs to the base of the seat to add strength and prevent them twisting.