The Society of the Plastic Industry established a classification system in 1988 to let recyclers and consumers identify different types of plastic. Plastic types are separated based on the codes allocated by international agreement and also by chemical composition.
Plastic labelled with an SPI code 1 is created using polyethylene terephthalate, which is known as PET/PETE. Containers made using PET absorb flavours and odours from drinks and foods that are stored in them. Products made using PET are easy to recycle. It is used to make common household items such as combs, jars, bean bags, and bottles. Recycled PET is used to make the filling material in winter clothing, carpets etc.
Plastic marked with an SPI code 2 is made using HDPE. Products made using HDPE are absolutely safe and are not known to leak any chemicals into drinks and foods. HDPE products are easy to recycle. Usually shampoos & conditioners containers, milk containers, detergents boxes are made of HDPE. Recycled HDPE is used in making fencing, plastic crates etc.
Plastic marked with an SPI code 3 is made of PVC. Generally, PVC is not recycled and can be harmful if food is stored in containers made using the material. PVC is generally used in making plumbing pipes. Recycled PVC is used in making industrial-grade items and home flooring.
Plastic labelled with an SPI code 4 is manufactured using LDPE. LDPE is not often recycled, but it can be recycled for certain things. LDPE is flexible and long-lasting. Since it doesn’t leach harmful chemical, it is safe to be used to store edible items. Squeezable bottles, plastic cling wrap, plastic grocery bags are made using LDPE. Recycled version of LDPE is used in making furniture, garbage cans etc.
Plastic that is labelled with an SPI code of 5 is made using PP or polypropylene. PP can be recycled but it is not widely accepted for recycling. It is usually used to make syrup bottles, plastic diapers, stadium cups etc. Durable items like battery cables, ice scrapers are made using recycled PP.
Polystyrene is marked with an SPI code of 6; It is also known as Styrofoam. Recycling PS consumes a lot of energy, which makes it less popular recyclable plastic. PS is used in making packing foam, disposable coffee cups, plastic cutlery etc. Things like plastic rulers and license plate frames are made with recycled PS.
The SPI code 7 is allocated to miscellaneous types of plastic. The plastics that are included in the category are polycarbonate and polylactide. CDs and DVDs are made of these types of plastics which are difficult to recycle.
If you are not familiar with polymers then SPI code can be confusing for you, but this guide helps you identify the right plastic type for your use.