First identify the property and the object
Examining composition, causes of failure and conformity with stated characteristics requires different source materials. It is useful for the assignment to identify the specific product, disputed parameter and period to which the question relates. Wording such as «check everything» does not help select methods or the required sample quantity.
Do not lose the sample's provenance
A measurement result must be linked to the object, sampling location and preparation method. If a fragment is submitted without information about where it came from, laboratory precision does not remove the uncertainty about its provenance.
- Retain markings and documents for the specific item or batch.
- Package materials from different areas separately.
- Report exposure to moisture, temperature, reagents and repairs.
- Agree destructive sampling before altering the product.
A finding on composition is not equivalent to a finding of suitability for every application. Assessing properties may require separate tests and information about operating conditions.
On this subject: Comparing two material samples: why provenance and sampling conditions matter.