How to Verify Silica-Free Claims: Evidence Checklist

Why Verification Matters

Every manufacturer now claims their product is “silica-free” or “low-silica.” But the evidence backing those claims varies dramatically. Some brands provide detailed SDS (Safety Data Sheet) documentation with independent third-party lab testing. Others rely on vague marketing language with no substantiation. As an architect, specifier, or buyer, you need to know the difference.

The Verification Pyramid

Not all evidence carries equal weight. Here’s how to rank what you receive:

The 10-Point Verification Checklist

1. Request the Current SDS

Ask for the most recent SDS. It should be less than 12 months old and list crystalline silica (CAS 14808-60-7) with a percentage. If silica isn’t listed at all, that’s a red flag – most engineered stones contain some form of quartz, and silence is not the same as absence.

2. Check the Lab Report Date

Any lab report should be within 24 months. Product formulations change. An SGS report from 2022 doesn’t guarantee a 2026 batch is the same formulation. Ask: “Is this test from the current production run?”

3. Verify the Lab’s Accreditation

Look for ISO/IEC 17025 accreditation on the lab report. If the testing lab isn’t accredited, the results aren’t externally auditable. Acceptable labs: SGS, Bureau Veritas, Intertek, Eurofins, ALS, TUV.

4. Match Product Name to Report

The product name on the lab report must match exactly the product you’re buying. “Quartz Surface Q10” on the report and “Premium Q10 Series” in the order are not the same thing. Partial name matching doesn’t count.

5. Know Your Thresholds

Different regulations define “silica-free” differently:

• Australia (2024 ban): No engineered stone containing crystalline silica. Zero tolerance.
• Cal/OSHA: < 0.1% crystalline silica in material = silica-free for some applications
• EU (proposed): Various thresholds under discussion
• Industry marketing: Often “low silica” = < 3-5%, not zero

6. Ask for Batch-Level Testing

A single lab report for a product launched 3 years ago isn’t enough. Raw material sources change, factory processes drift. Request batch-coded test results for your specific order.

7. Check the Testing Method

XRD (X-ray diffraction) is the gold standard for crystalline silica quantification. XRF (X-ray fluorescence) measures total elemental silicon, which overestimates silica content (it includes non-crystalline silicates). Know what method was used and what it actually measures.

8. Verify the Sample Chain

Who sent the sample to the lab? Ideally, a buyer or third-party inspector. If the manufacturer sent it, you’re trusting their sample selection. For high-value projects, send your own sample.

9. Cross-Reference with Regulator Lists

Check whether the product appears in any regulator databases (SafeWork Australia prohibited products list, OSHA enforcement records, NIOSH hazard alerts). Absence isn’t proof of safety, but presence is a clear warning.

10. Document Everything

Save SDS, lab reports, email correspondence, and purchase orders in a single project file. If a claim is ever questioned – during a specification review, site inspection, or legal dispute – your documentation is your defense.

Red Flags to Watch For

• “Proprietary formula” excuse – Legitimate silica-free products can disclose content without revealing trade secrets. SDS requires it by law.
• SDS older than 3 years – Formulations change. Expired documentation is not evidence.
• “Tested by our in-house lab” – Self-testing is not independent verification. Require third-party accreditation.
• No CAS number for silica on SDS – If crystalline silica (14808-60-7) isn’t listed, ask why.
• “Meets OSHA limits” without numbers – That could mean anything from 0.01% to 50%. Get the percentage.

Recommended Workflow

1. Request SDS from manufacturer (before placing order)
2. If SDS shows silica > 0%, request independent lab report
3. If no lab report exists, offer to split testing cost or send sample yourself
4. If manufacturer refuses or deflects, find another supplier
5. Document everything in your project file