Inter-Laboratory Coating Comparisons: Exchange a Shared Reference Panel

Two laboratories can report different results because they tested different specimens, used different methods or handled the same method differently. Sending only the final numbers rarely identifies the cause. A shared-reference exercise helps narrow the disagreement.

Agree the comparison before shipping

Specify the property, method, specimen conditioning, measurement locations and reporting units. Decide whether laboratories will measure the same travelling specimen or matched specimens prepared together. A travelling specimen can change during transport and handling, so its history must accompany it.

Include a stable reference

Choose a reference appropriate to the measurement and maintain its handling instructions. Ask each laboratory to measure it alongside the coating specimens. Retain raw observations, instrument settings and any invalidated results with reasons.

Pattern	Possible investigation
Reference and samples shift similarly	Method implementation or instrument difference
Reference agrees, coating samples differ	Specimen preparation, location or material sensitivity
Travelling specimen changes over time	Transport, handling or ageing

Compare paired observations

Use the same identified specimen or location where the method permits. A difference between laboratory averages is difficult to interpret if one measured only favourable areas and the other used a fixed map.

Do not declare a winner prematurely

Agreement between two laboratories does not prove universal accuracy, and disagreement does not automatically make one incompetent. Review uncertainty, traceability and suitability of the method for the coating and substrate.

The practical output is an agreed measurement procedure and a documented explanation of any remaining difference. If the result will support a commercial claim, obtain appropriate technical review before combining incompatible laboratory results into a single attractive number.

Related guides

• Planning a Real-World Field Trial for Ceramic Coatings
• Gloss Improvement from Coating: Use the Same Prepared Surface as the Reference
• A Coating Measurement Uncertainty Budget with a Worked Example

Ask NANOLAB about your surface and intended use. For application and care, use the current instructions for the exact product.