Resin identification code

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Sorted household plastic waiting to be hauled away for reprocessing.
Polypropylene lid of a Tic Tac box, with a living hinge and the resin identification code under its flap

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 is used internationally. The primary purpose of the codes is to allow efficient separation of different polymer types for recycling. Separation must be efficient because the plastics must be recycled separately. Even one item of the wrong type of resin can ruin a mix.

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. In this case, other text and labels are used to indicate the material(s) used. Previously recycled resins are coded with an "R" prefix (for example, a PETE bottle made of recycled resin could be marked as RPETE using the same numbering).

These codes do not indicate how hard the item is to recycle, nor how often the plastic may be recycled. It is an arbitrarily agreed upon code that has no other meaning aside from identifying the polymer used in manufacturing the specific plastic to facilitate future recycling of the plastic.

The Unicode character encoding standard includes the resin identification codes, between code points U+2673 and U+2679 inclusive in the Miscellaneous Symbols block. The generic material recycling symbol is encoded as code point U+267A.

Table of resin codes[edit]


Recycling number Image Unicode symbol Alternate image # Alternate image 0# Abbreviation Polymer name Uses Recycling
1 ♳
PETE or PET Polyethylene terephthalate Polyester fibers (Polar Fleece), thermoformed sheet, strapping, soft drink bottles, tote bags, furniture, carpet, paneling and (occasionally) new containers.

(See also: Recycling of PET bottles)

Picked up through most curbside recycling programs.
2 ♴
HDPE High-density polyethylene Bottles, grocery bags, milk jugs, recycling bins, agricultural pipe, base cups, car stops, playground equipment, and plastic lumber Picked up through most curbside recycling programs, although some allow only those containers with necks.
3 ♵
PVC or V Polyvinyl chloride Pipe, Window profile, Siding, fencing, flooring, shower curtains, lawn chairs, non-food bottles and children's toys. Extensively recycled in Europe, 481,000 tonnes in 2014 through Vinyl 2010 and VinylPlus initiatives.
4 ♶
LDPE Low-density polyethylene Plastic bags, 6 pack rings, various containers, dispensing bottles, wash bottles, tubing, and various molded laboratory equipment LDPE is not often recycled through curbside programs, but some communities will accept it. Plastic shopping bags can be returned to many stores for recycling.
5 ♷
PP Polypropylene Auto parts, industrial fibers, food containers, and dishware Number 5 plastics can be recycled through some curbside programs.
6 ♸
PS Polystyrene Desk accessories, cafeteria trays, plastic utensils, toys, video cassettes and cases, clamshell containers, packaging peanuts, and insulation board and other expanded polystyrene products (e.g., Styrofoam) Number 6 plastics can be recycled through some curbside programs.
7 ♹
OTHER or O Other plastics, such as acrylic, nylon, polycarbonate, and polylactic acid (a bioplastic), and multilayer combinations of different plastics Bottles, plastic lumber applications, headlight lenses, and safety shields/glasses. Number 7 plastics have traditionally not been recycled, though some curbside programs now take them.

Availability of recycling facilities[edit]

Use of the recycling symbol in the coding of plastics has led to ongoing consumer confusion about which plastics are readily recyclable. In many communities throughout the United States, PETE and HDPE are the only plastics collected in municipal recycling programs (e.g. Mackinaw City, Michigan[3]). 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.[4])

Possible new codes[edit]

In 2007, a State Senate bill in California (SB 898) proposed adding a "0" code for compostable polylactic acid.[5] However, this provision of the bill was removed before passage.[6][7]

There is a rapid expansion of materials converted to filament for 3-D printing from recyclebot technology so there has been a large expansion of resin identification codes has been proposed. [8]

See also[edit]


  1. ^ "Plastic Packaging Resins" (PDF). American Chemistry Council. Retrieved 2011-08-22. 
  2. ^ "What Do Recycling Symbols on Plastics Mean?". Good Housekeeping. Retrieved 2014-01-17. 
  3. ^ Mackinaw City
  4. ^ "What is Recyclable" from the City of Los Angeles Bureau of Sanitation website.
  5. ^ Full text and version history of California State Senate Bill 898
  6. ^ Bill summary from Californians Against Waste, an environmental group
  7. ^ SB 898 Senate Bill – AMENDED
  8. ^ Emily J. Hunt, Chenlong Zhang, Nick Anzalone, Joshua M. Pearce, Polymer recycling codes for distributed manufacturing with 3-D printers, Resources, Conservation and Recycling, 97, pp. 24-30 (2015). open access

External links[edit]