Silicone Parts Fail After Sterilization: 5 Proven Fixes

Silicone is chosen for medical components because it survives sterilization. Autoclave, EtO, gamma, electron beam—silicone handles all of them better than most materials. But 'survives' doesn't mean 'unchanged.' In fact, silicone parts fail after sterilization more often than most engineers expect—not because the material is wrong, but because the design didn't account for what sterilization does to it over time.

Sterilization changes silicone. It can increase hardness, increase compression set, reduce elasticity, and alter surface properties. In most cases, the changes are small enough that the part still works. But when the design has no margin, even a small change is enough to cause a failure.

I've seen this play out repeatedly. A silicone component passes all validation testing. It launches. Then, after months of field use and repeated sterilization, it starts to leak, crack, or lose sealing force. The material didn't fail. The design didn't account for what sterilization would do to the material over time.

The frustrating part is that this failure mode is predictable. It's not a mystery. It's a gap in validation. And it can be closed before the device ever reaches a patient.

Why Silicone Parts Fail After Sterilization: What Sterilization Actually Does

The key insight: the change depends on the formulation, the dose, and the number of cycles. A part that survives one autoclave cycle may fail after fifty. A part that passes gamma at 25 kGy may fail at 50 kGy. A part that performs perfectly in a single-use device may behave completely differently in a reusable device that is sterilized weekly for three years.

Why This Gets Missed

Validation testing is often done on as-molded parts, or on parts sterilized once. That data doesn't predict what happens after the device is used and re-sterilized dozens of times over its life.

There are three common reasons this happens:

The validation protocol was written for a single-use device. The device was later repositioned as reusable, but the sterilization testing wasn't updated.

The sterilization method was changed late in development. The device was validated with EtO, then switched to gamma for cost or logistics reasons. The silicone was never re-tested.

The supplier's data was used instead of the customer's data. The silicone supplier tested a generic sample. The customer's actual part, with its actual geometry and wall thickness, was never tested.

This is why silicone parts fail after sterilization in the field even though they passed initial validation. The validation protocol was written for a single-use device, but the device was later repositioned as reusable—and the sterilization testing was never updated.

For reusable devices, the correct validation is: test after the maximum number of sterilization cycles the device is designed for. For single-use devices, test after the actual sterilization dose. For either, test the properties that matter for the application—compression set, hardness, sealing force, tear strength.

What to Specify and Test

We test sterilization effects on every formulation we recommend for reusable devices. If a formulation can't hold its properties after the required number of cycles, we reformulate before the customer ever sees a problem.

This is not a cost center. It's risk reduction. One field failure caused by sterilization-induced property change can cost more than a decade of testing. According to ISO 10993-1:2025, biological evaluation must consider exposure duration—and sterilization-induced changes are part of that evaluation. ASTM D395 provides the standard test method for compression set.

The Bottom Line

Silicone survives sterilization. But it doesn't survive unchanged. The question isn't whether silicone parts fail after sterilization—it's whether your design has margin for the change. Test after sterilization, test after repeated cycles, and design with margin. If your supplier doesn't have this data, ask why.

Guangdong Exnan Technology Co., Ltd. focuses on medical-grade SR and LSR manufacturing, ensuring product safety and reliability from the material source for global medical customers.For more information, please visit our website: www.exnan.com