Start plastic color measurement by choosing the optical mode. Opaque reflectance, translucent reflectance with controlled backing, and transparent/translucent transmission answer different questions and should not be treated as interchangeable.
| Sample and question | Method direction |
|---|---|
| Opaque moulding or plaque | Use a defined reflectance method, geometry, aperture and representative locations. |
| Translucent part judged against a backing | Use controlled backed reflectance; the result describes the specified sample/backing appearance. |
| Transparent film or plaque | Use a defined transmission method when the requirement concerns light passing through the material; backed reflectance is not a substitute for transmission color or haze. |
Control the part, not just the resin
Record thickness/path length, flatness or fixture, sample temperature, orientation, backing where relevant and any fluorescence/effect behaviour. Pellets can support a defined incoming-material check, but they are not automatically equivalent to the final moulding, plaque or film.
A practical method chain
First decide reflectance or transmission. Then decide SCI vs SCE for the finish question, geometry for the optical arrangement, aperture for the usable area and tolerance for the release decision. Use the plastics selection guide to verify the required geometry, aperture and material capability before choosing an instrument.
Last reviewed 21/09/2026 · Level: Intermediate
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