If your silicone sheets come into contact with food, skin, or liquids, ignoring leaching tests could lead to contamination or compliance failure.
Migration and leaching tests ensure silicone sheets don’t release harmful substances into food, liquids, or biological systems during use or processing.
I learned about the importance of these tests while developing a line of baby feeding mats. Even though the silicone was marketed as “food-grade,” it failed the migration test under European standards. That setback forced me to go deeper into what makes a silicone sheet truly safe.
What Is Material Migration and Leaching in Silicone?
Not all silicone is inert. Some leach chemicals when exposed to heat, oil, or acids.
Migration and leaching refer to the release of substances from silicone sheets into adjacent materials—such as food, water, or skin—especially under heat or long exposure.
Migration is often tested by simulating real-world conditions where the silicone contacts food, body fluids, or sensitive surfaces. Leaching involves exposure to solvents or simulants (like ethanol, acetic acid, or oil) to measure how much and what type of material is released.
These tests help determine:
- If the silicone is truly food-safe
- Whether it releases plasticizers, catalysts, or by-products
- How stable it is under heat and pressure
- If it’s suitable for baby, medical, or pharmaceutical use
When I tested low-cost silicone sheets from a new supplier, I discovered they leached volatile organic compounds (VOCs) when heated to 150°C. That disqualified them from use in any food-related product.
Why Do Migration and Leaching Matter?
One failed test can cost you certifications—or worse, damage your customer’s trust.
Migration and leaching tests are essential to confirm that silicone sheets meet international safety standards for food contact, skin exposure, and medical use.
Silicone is widely used because it’s chemically stable—but not all formulations are equal. Some lower-grade silicones use peroxide curing or fillers that can migrate into nearby substances. Over time, these compounds may cause:
- Off-tastes or odors in food
- Skin irritation
- Non-compliance with FDA, LFGB, or EU regulations
- Loss of mechanical integrity
Here’s a breakdown of common risks:
| Risk Type | Source | Impact |
|---|---|---|
| VOC Release | Residual curing agents | Taste, smell, and toxicity issues |
| Oil Migration | Silicone oil fillers | Greasy surfaces, poor bonding |
| Heavy Metal Leach | Impurities in pigments | Non-compliance with RoHS, REACH |
| Catalyst Leach | Incomplete crosslinking | Allergic reactions or discoloration |
When designing a medical-grade teether for infants, I had to ensure zero migration even after boiling or sterilizing. We only passed the test after switching to platinum-cured LFGB-certified silicone.
What Are the Key Testing Standards for Migration?
I used to think “FDA approved” was enough—until a European distributor asked for LFGB reports.
Common migration testing standards include FDA 21 CFR 177.2600 (U.S.), EU 10/2011 (Europe), and LFGB (Germany)—each with specific simulants, temperatures, and testing durations.
These tests simulate real-world contact:
| Standard | Region | Simulants Used | Common Use Case |
|---|---|---|---|
| FDA 21 CFR 177.2600 | USA | Distilled water, n-hexane | General food-grade compliance |
| EU 10/2011 | Europe | Ethanol, acetic acid, oil | All food contact materials |
| LFGB Section 30 | Germany | Olive oil, acetic acid | Baby, medical, and skin contact |
| ISO 10993-5 | Global | Extraction into fluids | Medical biocompatibility |
Each standard has different thresholds for acceptable migration levels. For example:
- FDA allows total extractables of ≤10 mg/in² for aqueous and fatty simulants.
- LFGB testing requires no visible color transfer, odor, or taste change in any simulant.
I always ask for both FDA and LFGB reports when ordering food-contact silicone. Clients in the U.S. might be satisfied with FDA, but EU partners usually demand LFGB.
What Testing Methods Are Used?
I used to think migration tests were just lab formality—until I saw the level of detail and control involved.
Migration tests typically involve soaking silicone sheets in specific food simulants at set temperatures and durations, then analyzing the leachate for extractables.
Here’s how it usually works:
- Cut samples from the final silicone product (not just raw sheet)
- Clean samples according to protocol
- Soak in chosen simulants (e.g., ethanol, acetic acid, oil)
- Incubate at specific temperatures (e.g., 40°C–100°C) for 2–10 hours
- Analyze the extractable compounds using:
- Gravimetric methods (mass change)
- GC-MS (gas chromatography)
- ICP-MS (metal leach testing)
- Sensory testing (odor, taste)
Testing labs usually issue a migration report listing:
- Total extractables (mg/dm²)
- Volatile content
- Specific substance residues (e.g., tin, platinum, formaldehyde)
- Observations on color or odor changes
We once failed a sensory test because a silicone sample gave off a “rubbery” smell after being soaked in olive oil at 70°C. We traced it back to low-purity peroxide curing agents.
How Can I Ensure My Silicone Sheets Pass Migration Tests?
Passing a migration test starts with good formulation—and a transparent supplier.
To ensure your silicone sheets are safe, work with suppliers who use certified materials, provide compliance reports, and conduct third-party migration testing.
Here’s what I look for when choosing silicone for food, baby, or medical applications:
- ✅ Platinum-cured silicone
- ✅ FDA 21 CFR 177.2600 and LFGB test reports
- ✅ No added oils or plasticizers
- ✅ High-purity pigments (RoHS compliant)
- ✅ Batch traceability and material certifications
If I’m creating a product that contacts food or skin, I never rely on a supplier’s marketing claims. I always ask for the actual migration test report or send samples to a certified lab myself.
We manufacture food-grade and medical-grade silicone sheets that are pre-tested for migration under FDA and LFGB protocols. Our materials are platinum-cured, free from fillers and oils, and designed for sensitive applications.
What Happens If a Silicone Sheet Fails a Migration Test?
I once lost a major order because our sheet showed discoloration during migration testing.
If a silicone sheet fails a migration or leaching test, it cannot be sold for food or medical use—it may require reformulation, purification, or switching to a higher-grade silicone.
Typical failure reasons:
- Use of peroxide-cured silicone with incomplete curing
- Presence of silicone oils or plasticizers
- Use of non-certified pigments
- Poor post-curing or lack of thermal aging
Here’s how I respond to a failed test:
- Request a full formulation breakdown from the supplier
- Run a retest with higher post-curing (e.g., 200°C for 4 hours)
- Switch to platinum-cured silicone with LFGB and RoHS approval
- Limit pigment and additives in food-contact areas
Sometimes, just choosing a different curing method solves the issue. In one case, switching from a peroxide-cured red sheet to a platinum-cured translucent version fixed the problem instantly.
Conclusion
Migration and leaching tests are essential for ensuring silicone sheets are safe for food, medical, and skin-contact use—never skip them when quality matters.
