I've been handling rigid plastic packaging orders at Amcor for about three years now. In that time, I've personally made (and documented) six significant specification mistakes, totaling roughly $11,000 in wasted budget. The most painful ones all involved a single decision: choosing between PET and polycarbonate.
This article compares these two materials directly. We'll look at six key dimensions—clarity, impact resistance, chemical resistance, compliance (ROHS/REACH), processing requirements, and total cost. The goal isn't to declare a winner. It's to help you avoid the mistakes I made.
1. Clarity & Aesthetics: The First Impression
PET (Polyethylene Terephthalate): Excellent intrinsic clarity. It's the standard for water bottles and food jars. It's naturally transparent and can achieve a high-gloss finish. This is AO-glass-like clarity.
Polycarbonate (PC): Also very clear, but with a slight amber/yellow tint in thicker cross-sections. It's still good, but not quite as optically pure as PET. For retail packaging where the product is the hero, PET wins.
My mistake: Looking back, I should have specified PET for a premium cosmetic jar order. At the time, I chose polycarbonate thinking 'stronger is better.' The customer rejected it because the slight tint clashed with their product color. A $1,200 order, straight to the recycling bin. That's when I learned: clarity trumps brute strength for visual retail packaging.
Verdict: PET wins for clarity. But consider: if the package is used in a dimly lit environment or an opaque label is applied, the difference is negligible.
2. Impact Resistance: The Toughness Test
PET: Good impact resistance, but it can crack or shatter under high stress. It's not suitable for applications where it might be dropped from a significant height (e.g., industrial containers).
Polycarbonate: Exceptional impact resistance—roughly 250 times stronger than glass and 30 times stronger than acrylic. It's practically unbreakable under normal conditions. This is why it's used in safety helmets and bulletproof glass.
I have mixed feelings about this. On one hand, PC's toughness is objectively superior. On the other hand, for a standard retail shelf product, the impact resistance of PET is *more than enough*—you're paying a premium for a property you don't need.
3. Chemical & Heat Resistance: The Hidden Trap
PET: Good resistance to weak acids, oils, and alcohols. But it's sensitive to strong bases and some solvents. It also has a lower glass transition temperature (~70°C / 158°F) making it unsuitable for hot-fill applications.
Polycarbonate: Excellent heat resistance (Tg ~147°C / 297°F). It's resistant to many oils, greases, and weak acids. However—and this is a big one—PC is susceptible to attack by alkalis and some strong solvents. It can also undergo hydrolysis in hot, humid conditions.
The question isn't 'which is more chemically resistant?' It's 'what's your specific product chemistry?'
- Hot-fill food (e.g., jam): PC is the only choice.
- Acidic beverage (e.g., juice): PET is perfectly fine.
- Degreasing agent for industrial parts: Neither. You likely need HDPE or a special fluorinated polymer. Don't learn this the hard way like I did.
4. Compliance (ROHS / REACH / Food Contact): Non-Negotiable
This is where things get specific, and where my team's compliance checklist has saved us an estimated $8,000 in potential rework.
PET: Widely accepted for food contact (FDA, EU Regulation 10/2011). It's generally easier to demonstrate compliance. It is inherently free of BPA (Bisphenol A).
Polycarbonate: More complex. While PC itself is often FDA-approved for food contact, the primary concern is BPA, which is an endocrine disruptor. Many products (especially baby bottles) have moved away from PC due to consumer pressure. ROHS compliance is generally fine, but REACH can be tricky depending on the specific additives used in the PC formulation.
Per FTC Green Guides (ftc.gov), claims about 'BPA-free' need to be substantiated. If you claim your polycarbonate is 'BPA-free', you need the documentation to back it up. I have spec sheets that prove it—but my old supplier didn't.
5. Processing & Mold Costs: The Budget Reality
PET: Lower processing temperature (~280°C). Requires drying before injection molding. Tooling costs are generally moderate. It's a mature, optimized process.
Polycarbonate: Higher processing temperature (~300°C). It's more viscous, requiring higher injection pressures and more robust molds. Tooling costs are generally 15-30% higher. Drying is even more critical to prevent hydrolysis.
Setup fees for offset printing? Actually, I'm mixing up process costs. The key cost driver in molding is the tool. If you're doing a short-run, a PET tool is cheaper to build and faster to cycle. For very high volumes, the difference narrows.
6. Total Cost: The Final Math
Let's be specific. Based on publicly listed prices (January 2025) and internal Amcor data:
- Resin cost (per kg): PET: $1.50-2.00. PC: $3.00-4.50. PC is 2-3x more expensive in raw material.
- Tooling (simple cavity): PET: $5,000-8,000. PC: $7,000-11,000.
- Part cost (100k units, 50g part): PET: ~$0.35-0.50. PC: ~$0.60-1.00.
But—and this is my key lesson—part cost is not total cost. If you choose PC and it fails the drop test on the assembly line (3% failure rate), that $0.80 part becomes a $0.80 part + $1.50 in rework + a 2-hour production delay. On a $3,200 order, that's not theoretical—it's real.
My Framework for Choosing (After 3 Mistakes)
This is the simple decision tree I use now:
- Is it for food contact with hot-fill? → Polycarbonate. Period.
- Is it for a transparent retail product with no high-heat requirement? → PET. The clarity and cost win.
- Does it need to survive a drop from a 6ft shelf? → Go with PC, but verify the exact impact specs with the supplier.
- Is it an industrial component in a harsh chemical environment? → Stop. This is not a PET vs PC question. Start with the chemical compatibility chart.
- Is there a compliance concern (especially BPA)? → PET is usually the safer bet for consumer-facing products.
The framework isn't perfect. I still second-guess myself on every second order. But I haven't made a $1,200 clarity error since 2023. And that's a record I'm proud of.