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Plastic Identification Codes

4 Ratings: 5.0
A set of symbols placed on plastics to identify the polymer type.

The SPI resin identification coding system is a set of symbols placed on plastics to identify the polymer type. It was developed by the Society of the Plastics Industry (SPI) in 1988, and used internationally. The primary purpose of the codes is to allow … see full wiki

1 review about Plastic Identification Codes

Plastic Resin Identification Codes make recycling easier

  • Feb 9, 2010
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I'm sure you've noticed a recycling symbol with 1, 2, 3, 4, 5, 6 or 7 along with letters on most plastic products . So what are these exactly? The SPI Resin Identification Coding System is a set of symbols placed on plastics to identify the polymer type. The symbols used in the code consist of arrows that cycle clockwise to form a rounded triangle and enclosing a number, often with an acronym representing the plastic below the triangle. When the number is omitted, the symbol is known as the universal Recycling Symbol, indicating generic recyclable materials. It was developed by the Society of the Plastics Industry (SPI) in 1988, and used internationally. Let's take a look at the 7 plastic identification codes.


Polyethylene Terephthalate (PET, PETE) Clarity, strength, toughness, barrier to gas and moisture. Soft drink, water and salad dressing bottles; peanut butter and jam jars
High Density Polyethylene (HDPE) Stiffness, strength, toughness, resistance to moisture, permeability to gas. Milk, juice and water bottles; trash and retail bags.
Polyvinyl Chloride (PVC) Versatility, clarity, ease of blending, strength, toughness. Juice bottles; cling films; PVC piping
Low Density Polyethylene (LDPE) Ease of processing, strength, toughness, flexibility, ease of sealing, barrier to moisture. Frozen food bags; squeezable bottles, e.g. honey, mustard; cling films; flexible container lids.
Polypropylene (PP) Strength, toughness, resistance to heat, chemicals, grease and oil, versatile, barrier to moisture. Reusable microwaveable ware; kitchenware; yogurt containers; margarine tubs; microwaveable disposable take-away containers; disposable cups and plates.
Polystyrene (PS) Versatility, clarity, easily formed Egg cartons; packing peanuts; disposable cups, plates, trays and cutlery; disposable take-away containers;
Other (often polycarbonate or ABS) Dependent on polymers or combination of polymers Beverage bottles; baby milk bottles; electronic casing. Source: Wikipedia: Plastic recycling


Many plastics can be recycled, but not all, so they need to be separated into their different polymer types.  The Plastic Resin Identification Codes provide a valuable source when it comes to knowing what can and cannot be recycled.   These codes are the equivalent to the nutrional value listings on food products.  We would be lost without those, wouldn't we?

In most communities throughout the United States, PETE (#1) and HDPE (#2) are the only plastics collected in municipal recycling programs. Some regions, though, are expanding the range of plastics collected as markets become available (Los Angeles, for example, recycles all clean plastics numbered 1 through 7).  Check with the local recycler in your area.

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August 20, 2011
Well done. Unfortunately, my region's recycling program only processes PETE and HDPE.
July 13, 2011
This is a good coverage of material science structure of matter applied to plastic containers and receptacles for recycling purposes.
February 10, 2010
Nice review but this can get mighty confusing. Good job
January 05, 2011
Excellent piece. Well written, nicely illustrated and very informative!
February 10, 2010
Great review! I already recycle much of my garbage, but I'm glad to see someone clearing up the confusion with those numbers. I used to live in California, actually, in Murrieta, and the garbage service we had provided one can for garbage, one for twigs, leaves, etc. for when we trimmed our plants, and another for all of our recyclables. I suppose they sorted them later on. It made it MUCH easier.
February 10, 2010
This is great!  Very informative and helpful.  I just moved to a new city not too long ago, so thanks for the reminder to look up the recycling programs around here! :)
February 10, 2010
I'd always wondered about this, and never knew what the numbers meant until now. Thanks!
February 10, 2010
great review Clay. Very informative. I'm glad I live in LA and they recycle all types. Maybe that makes up for some of the air pollutants our freeways create... or a small bit hopefully.
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