During thickness testing, what should you do if the surface has excessive irregularities?

• A. Use a new SFRM batch
• B. Stop testing
• C. Reposition gauge to closest uniform area
• D. Increase gauge size

Answer: (C)

Thickness measurements depend on the gauge sitting flush on a flat, uniform surface so the reading reflects the material thickness, not surface contours. When the surface has excessive irregularities, the gauge can’t contact properly, causing unstable or biased readings. The best approach is to move the gauge to the closest area that is uniform and measure there, so the result accurately represents the sprayed material’s thickness. If needed, take multiple readings in that area to confirm consistency. Switching batches, stopping the test early, or enlarging the gauge won’t fix the geometry issue and can lead to misleading data.