What Are The Categories of Plastic Jars?
The Society of the Plastics Industry (SPI) developed a system to help identify plastic containers, bottles and jars, marking each one with a number (SPI Code), usually molded into the bottom. Whether you are collecting, buying or recycling, knowing which type of plastic a product is made from can help you determine what to recycle and how to properly dispose of your discarded items.

SPI Code 1: Polyethylene Terephthalate
Also known as PET or PETE, this is a thermoplastic resin that is often used for beverage and food storage containers. It has excellent oil barrier properties, a good alcohol and solvent barrier, as well as a fair water barrier.

SPI Code 2: Low-Density Polyethylene
LDPE is another common type of plastic marked with a SPI code 2. It can be durable and flexible, and does not release harmful chemicals into objects. It is often found in milk jugs, detergent and juice bottles, butter tubs, toiletries containers and other everyday use items.

SPI Code 3: High-Density Polyethylene
HDPE is the most commonly used type of plastic marked with a SPI Code 3. It is durable, opaque and a strong material that can withstand temperatures. It is often found in milk jugs, laundry and dishwasher detergent bottles, butter tubs, and toiletries containers.

SPI Code 4: Low-Density Polyethylene
This is a thinner type of plastic that is often found in grocery bags and shrink wrap. It can be recycled, but not as efficiently as other types of plastic.