01
Connect the sample to the order
The sample label, quotation and purchase order should identify the same material. Record source, product description, dimensions and permitted thickness range. Ask whether a sample represents normal variation or a specially selected piece. A single attractive tile cannot show the range that will arrive across several pallets.
02
Read the evidence in context
Check the laboratory, sample identification, test date, methods and units on any report. Ask the supplier to explain how the tested material relates to the offered slate. A classification describes specified material properties; it does not establish the quality of the proposed roof layout, metalwork or workmanship.
03
Approve appearance as a range
Review multiple pieces in daylight. Record the intended color variation, surface texture and expected weathering. For blends, record proportions and how the crew will distribute them. Include photographs of the approved panel, but retain physical samples because screens and lighting can alter the apparent color.
04
Manage substitutions explicitly
A different source, thickness or size can affect weight, fastening, cuts and appearance even if the sales name sounds similar. Ask for a comparison against the approved submission and a written decision before delivery. Keep rejected and accepted revisions separate to avoid an outdated sample becoming the installation reference.