It is important to be able to easily and efficiently identify plastics and sort them by resin type. This is because even one piece of incorrectly sorted plastic can ruin an entire recycled batch! For this reason the Society of the Plastics Industry (SPI) developed a coding system for plastics.
Plastics that can be recycled for business purposes include:
- PET – Polyethylene Terephthalate – which is often used in the manufacture of soft drinks bottles
- HDPE – High Density Polyethylene – which is used in extrusions, injection moulding and in the manufacture of plastic bottles
- PVC – Polyvinyl Chloride – which is used for manufacturing pipes, cables, signs, clothes, flooring & glazing
- LDPE – Low Density Polyethylene – which is used for manufacturing plastic bags & corrosion-resistant surfaces
- PP – Polypropylene – which is often used for packaging
- PS – Polystyrene – which is often used for protective packaging
- Plastic Polymers – which have a wide range of uses
- Nylon – which is often used for making ropes, fabrics & machine parts
SPI resin identification coding system
All of the plastics listed previously can be identified by this simple universal system which is called the resin identification coding system. They are each assigned a number which is displayed within the universal recycling symbol shown above. The symbols can very slightly but each number is unique to a specific type of plastic. An interesting fact is that if the prefix R- is used (for example RPETE on a plastic bottle) then the resin has been previously recycled!
Each of these symbols is also represented by a Unicode code point. Code point U+267A is the code for the universal recycling symbol above.
Polymer Name | Resin identification code | Unicode |
PET – Polyethylene Terephthalate | U+2673 | |
HDPE – High Density Polyethylene | U+2674 | |
PVC – Polyvinyl Chloride | U+2675 | |
LDPE – Low Density Polyethylene | U+2676 | |
PP – Polypropylene | U+2677 | |
PS – Polystyrene | U+2678 | |
Other Plastics (Including Nylon) | ![]() |
U+2679 |