Tools & Microfiber2 min read

A Gloss Map for a Coated Bonnet: Find Variation Before Averaging

Map gloss readings across a coated bonnet to distinguish overall improvement from local variation hidden by a single average.

Updated · NANOLAB Knowledge

Editorial illustration: Lighting for Paint Correction and Ceramic Coating Inspection
Editorial illustration

A bonnet with one exceptionally glossy spot and several uneven areas can produce an attractive average. A location map preserves the pattern that an average removes. It also makes later inspections easier to compare.

Create a repeatable location grid

Select accessible positions suitable for the instrument’s measurement geometry. Keep away from edges, sharp curvature and locations where the instrument cannot sit correctly. Mark positions on a diagram or external reference, not by placing unsuitable adhesive on a fresh coating.

Use the same instrument settings, orientation and surface condition for baseline and later measurements. Verify the instrument according to its instructions. Record repeated readings at each location separately from variation between locations.

Read the pattern before the summary

Pattern Useful next check
One isolated low location Positioning, local residue and substrate history
A consistent edge-to-centre change Geometry and application pattern
All locations shift similarly Overall treatment or measurement condition

For illustration, readings of 88, 88, 88, 88 and 68 have an average of 84. A second surface with five readings of 84 has the same average but a different spatial profile. Whether the first surface is unacceptable depends on the agreed criteria and whether the low reading is valid.

Do not let the map invent a cause

A low reading does not prove missing coating. Curvature, paint texture, contamination and measurement placement can affect the result. Inspect the location, repeat the reading appropriately and compare with its own baseline before deciding on rework.

Keep appearance and numbers connected

Record photographs and observer notes alongside the map. If the instrument reports a difference that cannot be reproduced, investigate the method rather than polishing the panel to chase a number.

A useful report includes the location values, average, range and measurement conditions. It should also state which areas could not be measured reliably. That is a stronger basis for a coating decision than selecting the highest value from a bonnet and presenting it as the whole finish.

Technical references

The sources below support the stated concepts or describe their own methods. The worked scenarios are editorial examples, not NANOLAB test results.

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