Professional Detailing2 min read

Coating Pass Decisions Near a Limit: Agree the Decision Rule in Advance

A result close to an acceptance limit needs an agreed decision rule. Establish how measurement uncertainty is considered before testing rather than choosing a favourable interpretation after the value is known.

Updated · NANOLAB Knowledge

The key distinction

ILAC provides guidance on decision rules and conformity statements. For a coating buyer, the practical requirement is clarity between the laboratory and specification owner. The report should state what rule supports a pass or fail conclusion, especially when a result is near a boundary and different approaches could lead to different decisions.

Practical checks

  1. Define the specification and request the laboratory's proposed conformity rule.
  2. Agree the relevant treatment of uncertainty before work begins.
  3. Retain the rule with the result and any final acceptance statement.

Example

Illustrative example: a measurement falls just below a maximum limit, but its uncertainty extends beyond that limit. The printed value alone does not explain the agreed conformity decision. The laboratory should apply the pre-established rule rather than the buyer selecting whichever interpretation permits release.

Scope and limits

This guide does not prescribe a universal guard band or acceptance policy. The appropriate rule depends on the requirements and parties involved. Do not change it retrospectively to obtain a preferred result or present an unqualified pass when the report states a limitation.

Related guidance

Technical references: ILAC: guidance series and decision rules. These sources describe their stated methods or products; they do not certify NANOLAB products or establish compatibility with an unlisted surface.

Ask NANOLAB about the exact product and intended use. Use the current product documentation for formulation-specific instructions.

Professional Detailing2 min read

Pass or Numeric Result: Writing a Useful Coating Test Request

Decide whether a laboratory should report a measured value, an observation, a pass decision or a combination before commissioning a coating test. These outputs answer different questions and require different instructions.