When it comes to sterilizing lab equipment, autoclaving is a go-to method. But not all tubes are created equal, and tossing them all into the autoclave without checking can lead to unexpected damage—or worse, ruined samples.
In this post, we’ll walk you through how to identify which tubes are autoclave-safe, the key differences in plastic materials, and common overlooked mistakes. If you’ve ever melted a tube (or worried about it), this one’s for you.
🔥 What Is Autoclaving?
Autoclaving uses pressurized steam at 121°C (250°F) to sterilize labware and kill microorganisms. While it’s highly effective, not every type of plastic can withstand such high temperatures.
Some tubes will stay intact and ready to reuse. Others? They may melt, crack, or release chemicals you don’t want near your samples.
🧪 The Material Matters: PP vs. PS
Most lab tubes are made from either polypropylene (PP) or polystyrene (PS)—and that difference is everything when it comes to heat resistance.
| Material | Max Temp | Autoclave-Safe | Notes |
|---|---|---|---|
| PP (Polypropylene) | ~120–130°C | ✅ YES | Durable and heat-resistant. Ideal for autoclaving. |
| PS (Polystyrene) | ~70–90°C | ❌ NO | Brittle at high temperatures. May warp or crack. |
💡 Pro Tip: Just because a tube is transparent doesn't mean it’s PS. Always check the material code (often on the bottom or label).
⚠️ Hidden Dangers: Caps, O-Rings, and Labels
Even if the tube body is autoclave-safe, other parts might not be:
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Screw caps with rubber or silicone O-rings can degrade or deform.
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Labels and tapes may melt or leave residue.
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Tube racks made of plastic may bend under heat.
Also, if you autoclave a fully sealed tube, pressure may build up and cause rupture or leaks. Always loosen the cap slightly before sterilizing.
✅ WATSON Autoclave-Compatible Tubes
WATSON offers a full lineup of autoclave-ready lab tubes made from high-quality PP with excellent thermal durability:
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Centrifuge Tubes (1332 series): Withstand up to 20,000×g, ideal for sterilization and high-speed use.
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Microtubes (1942 series): O-ring-less screw caps offer airtight closure without compromising autoclave safety.
All products are manufactured in Japan under strict quality control for reliable performance, lot after lot.
📌 Summary: Know Before You Sterilize
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✅ PP tubes are autoclave-safe. PS tubes are not.
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❌ Don't forget caps, O-rings, and labels—they matter too.
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⚠️ Always loosen caps before autoclaving to avoid pressure buildup.
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🔍 Double-check material types before placing anything into the autoclave.
Your samples are valuable. Don’t risk them with the wrong tube.