Coating Test Fixtures: Check That the Holder Does Not Enter the Measurement Area

The key distinction

Fixtures can improve repeatability, but an unsuitable arrangement can introduce another variable. The laboratory should identify permitted contact areas and record the setup so later measurements use an equivalent configuration.

Practical checks

1. Map the holder's contact and clearance regions.
2. Confirm that the intended measurement area remains valid.
3. Retain a setup photograph or drawing with the method record.

Example

Illustrative example: a clamp partly covers the optical measurement footprint on a small coupon. The instrument may return a value, but that value may not represent only the coated target region.

Scope and limits

Do not remove a necessary fixture or modify equipment without appropriate approval. Resolve the specimen geometry through the instrument instructions and qualified laboratory review.

Related guidance

• Gloss Measurement: Keep the Instrument Footprint Inside the Test Area
• Foam Cannons on Coated Cars: What Foam Does and Does Not Do
• Water-Bead Photographs: A Camera View Does Not Automatically Measure Contact Angle
• Coating Inspection Lights: Lumens and Watts Answer Different Questions

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