How can I verify if a silicone keypad supplier uses premium silicone vs. recycled material?
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- Suey
- Issue Time
- Aug 14,2026
Summary
Verify silicone keypad material by requesting CoA, conducting FTIR/TGA lab tests, and checking mechanical properties. Premium silicone has consistent hardness, high tensile strength, and low compression set. FromRubber provides full material traceability.
🔍 The difference between premium silicone and recycled material is not obvious from a visual inspection. Recycled silicone can look identical but fails much earlier – losing force, cracking, or developing high contact resistance. Here is a practical verification framework to protect your instrument's reliability.
Documentation & Traceability
- ✓ Ask for certificates of analysis (CoA) for each batch
- ✓ Request material safety data sheets (MSDS) from the compounder
- ✓ Verify batch number traceability to the raw polymer supplier
- ✓ Check for third‑party material certification (e.g., UL, FDA)
Physical & Mechanical Tests
- ✓ Durometer (Shore A) – premium silicone is consistent; recycled varies
- ✓ Tensile strength – recycled material is lower (typically < 5 MPa)
- ✓ Tear resistance – premium silicone resists propagation
- ✓ Compression set – recycled material has higher permanent deformation
Laboratory Analysis
- ✓ FTIR spectroscopy – identifies polymer type and fillers
- ✓ TGA (Thermogravimetric Analysis) – detects inorganic fillers and impurities
- ✓ DSC (Differential Scanning Calorimetry) – checks Tg and crosslink density
- ✓ Elemental analysis – detects unwanted contaminants
Premium Silicone vs. Recycled – Key Differences
| Property | Premium Silicone | Recycled Silicone | Risk |
|---|---|---|---|
| Shore A Hardness | ±2 tolerance | ±5–8 tolerance | Inconsistent tactile feel |
| Tensile Strength | 6–8 MPa | 3–5 MPa | Cracking, early failure |
| Tear Strength | High (15–25 kN/m) | Low (8–12 kN/m) | Web tearing |
| Compression Set | <15% | >30% | Loss of force over time |
| Heat Aging (70h @ 200°C) | Hardness change <5 | Hardness change >10 | Embrittlement |
| Colour Consistency | Uniform | Streaking, cloudiness | Visual quality issue |
| Traceability | Full batch traceability | Limited or generic | No accountability |
Laboratory Test Checklist for Your Silicone Keypad Supplier
Supplier Audit – Questions to Ask
- Who is your raw material supplier? – Premium compounders are well‑known; generic suppliers are not.
- Can you provide a certificate of analysis (CoA) for every batch? – This is standard for premium material.
- Do you have a material change notification (MCN) procedure? – You must be informed if the compound changes.
- What is your compression set specification? – Premium silicone should be <15%.
- Can we witness a production run? – Physical verification is always stronger than paperwork.
At FromRubber, we source only virgin, premium‑grade silicone from ISO‑certified compounders. We provide full material traceability, including CoA, batch records, and third‑party test reports. Our keypads are tested for hardness, tensile strength, tear resistance, and compression set on every production batch – and we invite our customers to audit our material control process at any time. We believe transparency is the only way to guarantee long‑term instrument reliability.
Putting It All Together
Verifying that your supplier uses premium silicone rather than recycled material requires a multi‑layered approach: documentation, physical testing, laboratory analysis, and supplier auditing. No single test is definitive, but the combination creates a reliable picture. Premium silicone offers consistent Shore A, high tensile and tear strength, low compression set, and clear FTIR profiles. Recycled material shows variability, lower mechanical properties, and often contains impurities detectable by TGA or DSC.
Do not rely on appearances alone. A keypad that looks perfect at delivery may degrade rapidly if made from recycled silicone. Investing in verification upfront saves costly field failures later.
✓ FromRubber offers full material transparency – CoA, FTIR, and mechanical test data are included with every order. We never use recycled silicone in instrumentation keypads.