Almost every plastic product carries a small triangle with a number in it. Most people read that mark as “this is recyclable.” That is not what it says. Recycling symbols 1-7 are an identification system, the way a fabric care label identifies cotton or wool. The number describes the resin. Whether that resin is collected where you live, and whether a plant can turn it back into usable material, are separate questions with separate answers.
This article covers where the numbers came from, what each one stands for, why the same code is handled differently from country to country, and the part consumer guides skip — what an industrial line actually looks at when it decides whether plastic goes into the product stream or the reject chute.
Recycling symbols 1-7 identify the resin family. They do not state whether an item is collected or reprocessed.
What the Recycling Symbols 1-7 Actually Are
The recycling symbols 1-7 are Resin Identification Codes. The Society of the Plastics Industry introduced them in 1988 so that sorters and reprocessors could tell one plastic from another. The standard is now maintained as ASTM D7611. The code is a material label, in the same sense that a steel grade or a paper weight is a material label.
The original mark used three chasing arrows around the number, which is exactly why so many people read it as a recycling claim. In 2013 the standard was revised and the chasing arrows were replaced with a plain solid triangle, specifically to stop the code from implying recyclability. Many moulds still in service predate that revision, so both versions circulate on shelves today.
The solid triangle holding a number is a resin identification code. The Mobius loop of three chasing arrows is the separate universal recycling symbol.
It also helps to separate two marks that look similar. The Mobius loop — three chasing arrows with no number — is the general recycling symbol and, when it carries a percentage, indicates recycled content. The numbered triangle is the resin code. A package can carry one, both, or neither, and none of those combinations tells you what your local collection service will accept.
What Each Number Means from 1 to 7
The plastic recycling numbers each map to one polymer family, except code 7, which is a catch-all for everything the first six do not cover. The table below gives the full resin name, what it typically appears as, how realistic recycling is at industrial scale, and the route a plant would normally use.
Plastic recycling numbers 1-7 with resin names, typical products, and the industrial route each material follows.
| Code | Resin Full Name | Common Products | Industrial Recyclability | Typical Processing Route |
|---|---|---|---|---|
| #1 PET or PETE | Polyethylene terephthalate | Drink bottles, food trays, polyester fibre | Strong. Bottle streams have established end markets | Bottle sorting, label removal, crushing, hot alkaline washing, float-sink, flake sorting |
| #2 HDPE | High-density polyethylene | Milk jugs, detergent bottles, crates, pipe | Strong in rigid formats | Label and cap removal, shredding, hot washing, friction scrubbing, float-sink, drying |
| #3 PVC or V | Polyvinyl chloride | Pipe, window profile, flooring, blister packs | Only in dedicated streams. Must be kept out of PET and PE lines | Separate size reduction, then dedicated PVC granulating and pelletizing |
| #4 LDPE | Low-density polyethylene | Bags, stretch wrap, agricultural film, squeeze bottles | Workable when collected separately as a clean film stream | Anti-tangle shredding, multi-stage film washing, float-sink, two-stage dewatering, compacting pelletizing |
| #5 PP | Polypropylene | Caps, tubs, buckets, woven bags, automotive trim | Growing, but sensitive to colour mix and contamination | Shredding or crushing, hot washing, friction scrubbing, float-sink, pelletizing |
| #6 PS | Polystyrene | Foam packaging, disposable cups, rigid trays | Weak. Foam is bulky and carries little value per tonne | Densifying or compacting first, then conventional size reduction |
| #7 OTHER | Any resin outside 1-6, including polycarbonate, ABS, nylon, acrylic, PLA and multilayer laminates | Baby bottles, electronics housings, pouches, compostable cups | Case by case. The code identifies nothing specific | Requires resin identification before any route can be selected |
Read the last two columns together and the pattern behind the recycling numbers is clear. Codes 1, 2 and 5 have a settled route because their density behaviour is predictable and buyers exist for the output. Codes 3, 6 and 7 fail not because the polymer is unrecyclable in a laboratory, but because separating and cleaning it costs more than the recovered material is worth.
Why the Symbol Does Not Mean an Item Gets Recycled
A resin code states what a product is made of. It says nothing about three things that decide the outcome — whether a collection service near you accepts that format, whether a sorting facility can separate it economically, and whether anyone is buying the recovered resin. Miss any one of those and the item is landfilled regardless of its number.
Identification, collection, sorting, and end markets are four separate gates. The symbol only clears the first one.
Format matters more than the number in almost every borderline case. A rigid HDPE detergent bottle and an HDPE carrier bag both carry a #2. The bottle has a stable route through rigid washing lines. The bag is film, it wraps around sorting screens and rotors, and most kerbside systems exclude it for that reason alone. Same resin, same code, opposite outcome.
Size is the other quiet disqualifier. Items smaller than a credit card tend to fall through screening decks and end up in the residue fraction, so a #5 tub is recovered while a #5 cap of the same resin is not.
This is also the honest answer to “which code is not recyclable.” Nothing in the recycling triangle marks a resin as unrecyclable, because the system was never designed to carry that information. If you want the material-by-material view of what does and does not get recovered in practice, that is covered separately in our guide to what plastics can be recycled.
Why the Same Number Is Collected Differently Around the World
The plastic recycling codes are an international standard, but collection is not. Each region decides what to accept based on the sorting equipment its facilities have installed, the contracts it holds with reprocessors, and whether there is a buyer within economic shipping distance. A #5 tub accepted in one city is residue in the next one over.
Regional on-pack labels answer a different question from the resin code, and the Green Dot answers no recycling question at all.
Because the resin code answers the wrong question for consumers, several regions layered their own labels on top of it. In North America, How2Recycle prints instructions rather than a number — rinse this container, return this film to a store drop-off. In the UK, On-Pack Recycling Labels state plainly whether an item is widely collected by councils. Both exist because the numbered triangle could not tell anyone what to do with the packaging in their hand.
The mark most often misread is the European Green Dot. It looks like two chasing arrows, but it is a licensing symbol showing that the producer paid into a packaging recovery scheme. It carries no information about whether that specific package is recyclable, and it appears on plenty of packaging that is not.
What a Recycling Plant Reads Instead of the Number
No industrial sorting line reads the printed triangle. By the time material reaches a plant it arrives baled, crushed, dirty, and often label-side down, so the mark is unreadable in practice. Plants identify resin by physical properties instead — how the polymer reflects infrared light, and how it behaves in water.
Optical sorters at a material recovery facility scan each item with near-infrared light and match the reflected spectrum against known polymer signatures. It is the molecular structure being read, not the moulded-in code. This is also why black packaging is a persistent problem across the industry regardless of resin, because carbon black pigment absorbs the infrared and the sorter registers nothing at all.
A washing line separates by optical signature and density, not by the resin code printed on the packaging.
Density does the rest of the work, and here the numbers do line up with physics. PET at roughly 1.38 g/cm³ sinks in water. HDPE, LDPE and PP sit between about 0.90 and 0.96 g/cm³ and float. That single difference is what allows a float-sink tank to pull PET flakes down for collection while PP caps and PE label fragments are skimmed off the surface.
The SUHUI PET bottle sorting washing line runs both mechanisms in sequence. Whole bottles pass a manual sorting station and a high-speed optical sorter that ejects non-PET and heavily coloured bottles before crushing. A magnetic drum and eddy current separator take out ferrous metal and aluminium caps. After washing, flakes pass float-sink tanks, a zig-zag air separator, and a second optical stage that splits clear, light blue and green PET. Nowhere does anything look for a number.
Why One PVC Bottle Can Ruin a PET Batch
PVC is the reason resin codes matter industrially even though machines cannot read them. PVC sits at roughly 1.3 to 1.45 g/cm³, overlapping PET, so a float-sink tank cannot separate the two. If PVC reaches the washing stage it stays with the PET all the way to the extruder, and that is where the damage happens.
PVC and PET have overlapping densities, so PVC has to be removed by optical sorting before crushing rather than in the wash.
PVC begins to decompose well below the temperature at which PET is processed, releasing hydrogen chloride as it does. In a PET melt that gas discolours the polymer and breaks the chains, dropping intrinsic viscosity. A small fraction is enough to turn a clean batch yellow and push it out of specification for bottle-grade or fibre-grade use.
This is why the sequence on a well-built line is not arbitrary. SUHUI’s PET line rejects PVC bottles at the whole-bottle optical stage, before crushing, and the manual sorting station upstream removes PVC bottles and glass by hand as a second safeguard. Once a PVC bottle is crushed into 10 to 15 mm flakes and mixed into several tonnes of PET, no downstream stage on a mechanical line will get it out again.
PVC is not waste material — it simply needs its own route. Rigid PVC pipe, profile and sheet scrap runs on a dedicated PVC granulating and pelletizing line with its own temperature profile, kept entirely separate from PET and polyolefin streams.
From a Symbol on a Bottle to a Sorting Line
For a consumer the code is where the decision ends. For a recycler it is where specification starts. A buyer planning a line has to state the resin, the physical form the material arrives in, the contamination level, and the output the market expects — because those four together, not the number alone, determine the equipment.
The same resin code can lead to different equipment depending on the physical form the waste arrives in.
| Incoming Stream | Why the Code Alone Is Not Enough | Relevant SUHUI Line |
|---|---|---|
| Baled post-consumer PET bottles (#1) | Bales carry PVC bottles, sleeve labels, caps and metal that must be removed before crushing | PET Bottle Sorting Washing Line |
| Rigid HDPE containers (#2) | Caps and labels are often a different resin from the body, so density separation is essential | HDPE Rigid Milk Bottle Recycling Washing Line |
| Agricultural and packaging film (#4 and #2 film) | Film tangles on conventional rotors and arrives with soil and moisture, not just surface dirt | PP PE Soft Film Recycling Washing Line |
| Rigid PVC pipe, profile and sheet (#3) | Must be isolated from PET and polyolefin lines and run at its own temperature profile | PVC Granulating and Pelletizing Line |
| Bulky mixed rigid scrap of unknown code | Resin has to be identified before any wash configuration can be specified | Crusher and Shredder Equipment |
| Washed flakes ready for reuse | Flake purity and moisture, not the resin code, set what the pellet can be sold as | Plastic Recycling Pelletizing Line |
SUHUI builds both sides of that loop — the plastic recycling machine lines that turn waste into flakes and pellets, and the extrusion lines that turn those pellets into pipe and profile. Seeing where recovered resin ends up is what makes a code different from a specification.
Frequently Asked Questions
What do the 7 recycling symbols mean?
They are resin identification codes, not recyclability ratings. #1 is PET, #2 is HDPE, #3 is PVC, #4 is LDPE, #5 is PP, #6 is PS, and #7 covers every other resin including polycarbonate, ABS, nylon, acrylic, PLA and multilayer laminates. Each number names a polymer family and nothing else.
What are plastics 1, 2, and 5?
Number 1 is polyethylene terephthalate, used for drink bottles and food trays. Number 2 is high-density polyethylene, used for milk jugs, detergent bottles and pipe. Number 5 is polypropylene, used for caps, tubs, buckets and woven bags. These are the three plastic numbers with the most established industrial recycling routes.
What is the 5 symbol on plastic containers?
A 5 identifies polypropylene. It appears on yoghurt pots, margarine tubs, bottle caps, buckets, woven bags and automotive trim. Polypropylene floats in water at around 0.90 g/cm³, which is what allows a float-sink tank to separate PP caps from denser PET flakes during washing.
What number cannot be recycled?
No number is marked as unrecyclable, because the code was never designed to carry that information. In practice #3 PVC, #6 PS and #7 mixed resins are the hardest, but that reflects sorting cost, contamination and weak end markets rather than anything encoded in the symbol itself.
What numbers can go in the recycle bin?
That is decided by your local collection service, not by the number. Most programmes accept rigid #1 and #2 containers, many now take #5, and few accept #3, #6 or #7 at kerbside. Film and bags usually need a separate store drop-off even when they carry an accepted code.
Is number 7 on plastic safe?
Code 7 is a catch-all rather than a specific material, so the number alone identifies nothing about the item. It may be polycarbonate, ABS, nylon, acrylic, PLA or a laminate. Food-contact suitability is governed by the specific resin and the applicable regulation, never by the code.
How to identify plastic for recycling?
Consumers read the code. Industrial plants do not. Sorting lines identify resin by near-infrared spectrum and by density in a float-sink tank, because baled material is too dirty and deformed for a printed mark to be readable. For unknown feedstock, plants test a sample before specifying any equipment.
Conclusion
The recycling symbols 1-7 do one job well. They tell a reprocessor which polymer family an item belongs to, which is what the Society of the Plastics Industry designed them for in 1988. They were never meant to tell a household what to put in the bin, and the 2013 switch to a solid triangle admitted as much.
What decides whether plastic gets recycled happens further down the line — whether an optical sorter can pick the resin out, whether density separation can clean it up, and whether a single PVC bottle slipped past the reject gate. If you are evaluating a waste stream, describe the material, the form it arrives in, and the contamination you see, then contact SUHUI Machinery for a configuration built around it.
Sources
- U.S. Department of Energy — Consumer Guide to Recycling Codes — Reference for what each resin identification code covers.
- Association of Plastic Recyclers — APR Design Guide — Industry reference for recyclability, contamination limits and recovered material quality.
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