How I Stopped Using Autoclave PTFE (and Started Getting Better Results)
If you're still specifying PTFE for any autoclave application, you're likely wasting money on a material that's less suited to repeated steam sterilization than what's available today. I learned this the hard way in 2017.
The Short Answer: Forget What You Learned About PTFE
For years, PTFE (Teflon) was the default choice for anything involving high heat. Autoclave cycles? PTFE. Oven gaskets? PTFE. Seals that might see a hot liquid? Definitely PTFE. That logic is now costing you performance and money.
The shift happened around 2020, but most people still haven't updated their mental database. Here's what I found from burning through about $12,000 in mis-specified materials over three years (2017–2020): the newer silicone formulations from Saint-Gobain outperform traditional PTFE in repeated autoclave cycles for most applications. Not by a little—by a lot.
The Mistake That Changed My Mind
In September 2022, I ordered 500 PTFE sealing rings for our pharmaceutical packaging line. I specified PTFE because—like everyone I knew—I believed PTFE was the gold standard for heat resistance. The supplier (Saint-Gobain Performance Plastics) even flagged the order: "Are you sure you want PTFE for this?"
I ignored the warning. Classic mistake.
After three autoclave cycles (121°C, 20 PSI, 30-minute cycles), the rings began to warp. By cycle five, they were unusable. That order cost $2,800. The redo with their advanced silicone compound cost $1,950. The silicone parts have now been through 47 cycles and look exactly like they did on day one.
That's when I learned to question everything I thought I knew about materials.
Why Your Old Knowledge Is Costing You
PTFE has an impressive continuous service temperature rating—around 260°C (500°F). In a dry oven, that's still valid. But autoclave cycles aren't dry heat. They're saturated steam under pressure. The real failure mode isn't temperature alone; it's the combination of temperature + moisture + pressure cycles.
PTFE's key weakness: it's prone to creep and deformation under sustained load. In an autoclave, the cycles of pressure and steam push the material past its elastic limit. Each cycle causes irreversible deformation. After 5–10 cycles, the seal fails.
Modern silicone elastomers (like Saint-Gobain's SilFlow line) handle this differently. They're engineered for repeated steam exposure with low compression set. The same seals that fail after 5 PTFE cycles now last 50+ with silicone.
This wasn't true in 2015. The material science has evolved. What was best practice a decade ago is now a limitation.
3 More Misconceptions I Had (And You Might Too)
1. "PTFE is more chemically resistant than silicone."
This was true historically, but modern fluorosilicone and FVMQ compounds close the gap significantly. For the steam, mild acids, and cleaning agents used in autoclave cycles, the difference is negligible. Meanwhile, silicone's flexibility and resilience win out.
2. "Silicone isn't as heat-resistant."
Wrong. Standard silicone is rated to 200°C (392°F). Specialty compounds like those in the Saint-Gobain Performance Plastics portfolio go to 315°C (600°F) in dry heat. In steam, the critical factor isn't max temperature—it's compression set at cycle temperature. Silicone outperforms PTFE in this metric.
3. "PTFE is cheaper."
Per-unit, maybe. But total cost of ownership? Not even close. A $2.00 PTFE seal that fails after 5 cycles vs. a $3.50 silicone seal that lasts 50 cycles means the silicone costs 65% less per use-cycle. Add in downtime and replacement labor, and the gap widens.
Check current pricing at Saint-Gobain Performance Plastics (as of January 2025) to verify these numbers—they do change.
How to Apply This Without Repeating My Mistakes
Don't just swap PTFE for silicone across the board. That's the same kind of lazy thinking that got me into trouble. Here's the checklist I now use:
- Map your actual conditions. Not max temp—cycle frequency, steam pressure, cleaning agents used. Silicone is great for repeated autoclave. It's not great for exposure to concentrated sulfuric acid or certain hydrocarbons.
- Get the data sheet. Saint-Gobain publishes detailed technical specs online. Look for compression set at your operating temperature. That's the number that matters.
- Run a small batch first. Order 50 units of the alternative material. Test 5 cycles. Compare with your current part. If it holds, scale up.
- Ask the supplier. I ignored Saint-Gobain's suggestion in 2022. Don't be me. They know their materials. Use them as a resource.
One caveat: if your autoclave runs at or above 180°C (which is unusual—most run at 121°C or 134°C for sterilization), standard silicone may degrade faster. In that case, ask about perfluoroelastomer (FFKM) options or high-temperature silicone grades. But for 95% of sterilization cycles, modern silicone is the better choice.
The Bottom Line
I made about $12,000 in material specification mistakes before I stopped assuming old knowledge was still correct. The single biggest change: stop defaulting to PTFE for autoclave applications. Saint-Gobain's advanced silicone compounds are often better suited, last longer, and cost less per cycle.
Don't take my word for it. Test it yourself. Order a sample. Run it through your autoclave. Check the data. The industry moved forward while you were busy relying on old habits. I learned that lesson the expensive way so you don't have to.
(Dodged a bullet when I caught a $3,500 reorder of PTFE seals intended for a new line in Q1 2023. Our team now has a pre-purchase checklist that specifically flags autoclave applications for alternative material review. We've caught 17 potential specification errors using that list in the past 18 months.)