01
Start with traceability
Check producer, quarry, product, sample description, collection method and date. Confirm the supplier can connect the delivered pallet labels to the tested material.
02
Understand what was measured
Roofing-slate standards reference properties such as absorption, breaking load and weathering-related tests. Read the units, sample count and stated method rather than focusing only on a grade headline.
03
Use testing with visual quality control
Laboratory results do not inspect every delivered piece or replace sorting. Combine reports with representative samples, delivery inspection and workmanship requirements.