Surface finish can change both a color reading and the way a product looks. Treat color and gloss as related but separate quality characteristics; a color pass can coexist with a finish failure.
Why finish changes the result
Specular reflection travels in a direction determined by the illumination and surface. Whether it reaches the detector depends on measurement geometry; it is not simply “reflection toward the instrument.” Texture, orange peel, haze and gloss can therefore alter visual appearance and some color results.
| Condition | What it tells you |
|---|---|
| SCI color | Includes specular reflection and generally reduces the influence of gloss and texture changes on measured color. |
| SCE color | Excludes specular reflection and is more sensitive to finish and surface appearance. |
| Gloss measurement | A separate gloss-meter method reports gloss units at the angle required by the specification. |
For separate gloss measurement, ASTM D523 and ISO 2813 use 60° as the general geometry, 20° for high-gloss surfaces (commonly above 70 GU at 60°) and 85° for matt surfaces (commonly below 10 GU at 60°). The applicable material standard still takes precedence.
When gloss falls, diffuse reflection often rises. Under SCE this commonly makes dark colors read lighter even though the pigment formulation has not changed—one reason a part can appear to have a color shift when the underlying issue is surface finish.
A two-variable QC decision
A practical coating method can require both a color result under the agreed SCI/SCE condition and a separate gloss result. Record each limit and the actions for disagreement: a part can meet ΔE but fail gloss, texture or another appearance requirement. Neither SCI nor SCE alone captures every appearance attribute.
Continue with SCI vs SCE, integrating spheres, powder-coated metal and plastics.
Last reviewed 21/09/2026 · Level: Fundamental
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