Ultimate Guide to Packaging Plastics: Understanding PET, HDPE, PP & Resin Codes

Choosing the right plastic resin is one of the most critical decisions in product development and B2B packaging procurement. The plastic material you select directly influences your product's shelf life, chemical stability, packaging weight, shipping costs, and overall brand perception.

With dozens of plastic formulations available, how do you determine whether a PET bottle, an HDPE container, or a PP jar is best suited for your formulation? This comprehensive guide breaks down the Resin Identification Code (RIC) system, details the properties of the seven primary packaging plastics, and helps you select the ideal material for your industry needs.

Understanding Resin Identification Codes (RIC) & Key Packaging Selection Criteria

To standardize plastic identification and recycling globally, the Society of the Plastics Industry (SPI) introduced the Resin Identification Code (RIC) system in 1988. Represented by numbers #1 through #7 enclosed inside a chasing arrows symbol, these codes identify the specific plastic resin used to manufacture a container.

While RIC codes are essential for waste management and recycling sorting, B2B buyers must evaluate packaging plastics based on four primary performance factors:

1. Clarity & Visual Appeal: Does your product require crystal-clear transparency to showcase the formula (like glass), or does it benefit from opaque protection?
2. Chemical Compatibility: Can the plastic withstand volatile formulation ingredients such as essential oils, alcohol, acids, or active skincare compounds without degradation or leaching?
3. Barrier Properties: How effectively does the resin block oxygen, moisture, UV light, and carbon dioxide from spoiling the product?
4. Thermal & Physical Resilience: Will the container endure hot-fill processing temperatures, cold storage, or the physical impacts of e-commerce shipping?

The 7 Common Packaging Plastic Materials 

PET / PETE (Polyethylene Terephthalate) – Resin Code #1

What is PET / PETE?

Polyethylene Terephthalate is a strong, lightweight, and crystal-clear thermoplastic polymer derived from ethylene glycol and terephthalic acid. Celebrated in the packaging industry for its ability to mirror the optical brilliance and luxurious feel of glass, PET is entirely shatterproof and significantly lighter, dramatically lowering freight costs and transit breakage rates. It possesses a tightly packed molecular structure that yields an outstanding gas barrier against oxygen and carbon dioxide, making it the gold standard for preserving formulation potency, aroma, and shelf life in premium personal care and beverage products.

• Key Characteristics: Glass-like transparency, high strength-to-weight ratio, rigid impact resistance, and excellent gas/moisture barrier properties.
• Best Packaging Applications: Cosmeceutical serum bottles, Cosmo round lotion containers, straight-sided skincare jars, and beverage packaging.
• Compatibility Notes: Excellent for water-based products, mild topical cosmetics, and alcohol; avoid using with highly concentrated pure essential oils, strong solvents, or temperatures exceeding 140°F (60°C) which cause thermal distortion.

Explore FH Packaging’s collection of high-clarity PET Plastic Bottles & Jars.

HDPE (High-Density Polyethylene) – Resin Code #2

What is HDPE?

High-Density Polyethylene is a versatile, petroleum-based thermoplastic characterized by its highly linear molecular structure, which imparts high density, stiffness, and exceptional impact resistance. Naturally translucent to opaque, HDPE is a true workhorse in B2B packaging because it does not leach chemicals easily and exhibits superior Environmental Stress Crack Resistance (ESCR). It creates a formidable barrier against moisture, water vapor, and aggressive liquid chemical formulations, allowing it to safely house everything from active health supplements to heavy-duty industrial cleansers.

• Key Characteristics: Semi-rigid to rigid durability, translucent or opaque finish, high impact strength, and superior chemical and stress-crack resistance.
• Best Packaging Applications: Pharmaceutical packer bottles, roll-on deodorant containers, personal care squeeze bottles, and household chemical jugs.
• Compatibility Notes: Highly compatible with strong acids, alkalis, household chemicals, and alcohols; withstands cold storage down to -100°F (-73°C) and hot-fill processing up to 248°F (120°C).

Browse our durable HDPE Containers & Roll-On Bottles.

PVC (Polyvinyl Chloride) – Resin Code #3

What is PVC?

Polyvinyl Chloride is a rigid or flexible synthetic polymer containing chlorine, historically praised for its exceptional structural toughness, flame retardancy, and clarity. To make PVC flexible enough for packaging applications, plasticizers (such as phthalates) are added to the formulation. However, due to tightening global environmental regulations, recycling stream contamination, and potential chemical leaching concerns in beauty and medical applications, primary cosmetic packaging has largely phased out PVC in favor of safer, more recyclable alternatives like PET and PP.

• Key Characteristics: Durable, rigid or flexible (depending on plasticizers), weather-resistant, and chemically stable.
• Best Packaging Applications: Pharmaceutical blister packs, tamper-evident shrink bands, outer protective casings, and clear vinyl pouches.
• Compatibility Notes: Resistant to oils, acids, and alcohols, but vulnerable to aromatic solvents and high heat; restricted in many modern cosmetic packaging lines due to eco-compliance standards.

LDPE (Low-Density Polyethylene) – Resin Code #4

What is LDPE?

Low-Density Polyethylene is a flexible, highly branched thermoplastic polymer that prioritizes elasticity, squeezability, and impact toughness over rigid strength. Unlike HDPE, LDPE’s short and long-chain branching prevents tight molecular packing, creating a soft, pliable material that can endure continuous flexing and squeezing without cracking or losing its shape. This unique mechanical memory makes LDPE the primary choice for dispensing products that require user-controlled flow.

• Key Characteristics: Soft, flexible, translucent, excellent squeeze memory, high impact resistance at low temperatures, and good moisture barrier.
• Best Packaging Applications: Cosmetic squeeze tubes, flexible dropper bulbs, lip balm tubes, and precision dispensing squeeze bottles.
• Compatibility Notes: Ideal for creams, ointments, pastes, and liquid drops; offers lower oxygen barrier performance than PET or HDPE, so oxygen-sensitive formulas may require multi-layer barrier tubes.

Discover versatile Squeeze Tubes & Dropper Assemblies at FH Packaging.

PP (Polypropylene) – Resin Code #5

What is PP?

Polypropylene is a semi-rigid, highly versatile polyolefin polymer famous for its exceptionally high melting point (~320°F / 160°C) and dynamic fatigue resistance. Widely known in packaging engineering as the "living hinge" plastic, PP can be flexed repeatedly millions of times without fracturing or degrading. In beauty and B2B packaging, PP is the premier resin for functional components subjected to heat, mechanical motion, or lipid-heavy formulas (such as essential oils, waxes, and botanical butter) that would cause other plastics to craze or breakdown.

• Key Characteristics: High heat resistance (hot-fill and autoclave safe), superior fatigue resistance for living hinges, excellent oil/solvent resistance, and translucent finish.
• Best Packaging Applications: Bottle caps, dispensing pumps, lotion sprayers, twist-up deodorant sticks, and double-wall cream jars.
• Compatibility Notes: Outstanding chemical compatibility with essential oils, fatty creams, balms, solvents, and hot-filled formulas up to 212°F (100°C).

Check out our complete range of PP Caps & Dispensing Closures.

PS (Polystyrene) – Resin Code #6

What is PS?

Polystyrene is a rigid, naturally transparent thermoplastic made from monomer styrene that delivers glass-like optical clarity and a hard, crisp feel at a very economic price point. While PS offers an elevated, crystal-clear aesthetic for display-driven retail items, it is inherently brittle and offers low resistance to impact and organic solvents. Consequently, cosmetic brands frequently utilize modified styrene compounds (like AS or SAN) or pair PS outer shells with protective inner liners.

• Key Characteristics: Crystal-clear transparency, rigid structure, acrylic-like aesthetic, but low impact strength and low moisture barrier.
• Best Packaging Applications: Compact powder cases, clear sample jars, outer decorative caps, and luxury cosmetic display casing.
• Compatibility Notes: Suitable for dry powders, anhydrous gels, and short-term sample containers; prone to stress cracking when exposed to pure essential oils, alcohol, or sharp impacts.

Other / Category #7 (AS, Acrylic, Bioplastics & Multi-Layer)

What is Code #7 (Other Plastics)?

Category #7 is a comprehensive catch-all classification for resin formulations not encompassed by codes #1–#6, as well as multi-layer material blends and advanced engineering polymers. In modern packaging, this category includes premium materials like AS (Acrylonitrile Styrene) and Acrylic (PMMA), which offer heavy-wall, crystal-clear luxury aesthetics, as well as bio-based resins like PLA (Polylactic Acid) and multi-layer oxygen-barrier bottles designed for sensitive formulations.

• Key Characteristics: Highly customizable properties ranging from heavy-wall acrylic brilliance to biodegradable performance and multi-layer oxygen protection.
• Best Packaging Applications: Premium airless pump bottles, double-wall luxury jars, thick-wall serum bottles, and bio-based sustainable containers.
• Compatibility Notes: Varies by specific resin formulation; AS and Acrylic deliver exceptional cosmetic chemical compatibility with oils while providing a high-end luxury weight.

Image Credit Notice: Resin Identification Code symbols (#1–#7) referenced in this section are based on works created by Bhutajata (Wikimedia Commons), available under CC0 / Public Domain.

Plastic Materials Comparison Matrix

Use this quick-reference comparison matrix to evaluate resin specifications for your packaging development:

Matching Packaging Plastics to Your Specific Industry Requirements

Selecting the correct resin depends heavily on product formulation and target market expectations:

• Skincare & Beauty Packaging: Water-based serums and liquids look stunning in transparent PET or AS airless bottles. However, formulas containing high concentrations of essential oils, lipids, or active botanical extracts require PP or glass to prevent degradation.
• Pharmaceutical & Nutraceutical Packaging: Light-sensitive vitamins, capsules, and liquid medicines demand amber-colored PET or opaque HDPE packer bottles paired with Child-Resistant Closures (CRC) to guarantee compliance and shelf stability.
• Personal Care & Deodorants: Solid stick formulations and liquid roll-ons rely on PP and HDPE for their chemical durability against fragrance oils and smooth mechanical movement.

Sustainable Plastic Packaging Trends: PCR & Recyclability

As global sustainability regulations tighten and consumers demand eco-conscious choices, packaging sourcing is shifting toward circular economy solutions:

• Post-Consumer Recycled (PCR) Plastics: Utilizing PCR-PET and PCR-HDPE reduces virgin plastic production, lowers carbon footprints, and diverts waste from landfills without sacrificing durability or performance.
• Mono-Material Packaging Design: Traditional packaging often combines multiple resins (e.g., a PET bottle with a multi-material metal spring pump), making recycling difficult. Designing mono-material packaging (such as all-PP pumps and bottles) simplifies the recycling stream and boosts overall sustainability.

Read more about our environmental commitments at FH Packaging Sustainability Promise.

Sourcing Your Wholesale Plastic Packaging

Selecting the right plastic material balances formula protection, aesthetic appeal, shipping durability, and cost efficiency. Partnering with an experienced packaging supplier ensures that your selected containers meet rigorous quality and compatibility standards.

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