Masterbatch color cannot be described by pellet color alone. The concentrated pellet, carrier resin, let-down ratio, base polymer, processing temperature, dispersion and plaque thickness all affect the developed color. A robust specification states which specimen is authoritative.
Use a two-stage control plan
Stage 1: pellet screening. Measure comparable masterbatch pellets with a controlled cup method to detect major lot shifts or contamination. Stage 2: standard let-down. Blend the masterbatch into a defined natural resin at the specified concentration, process it under fixed conditions and measure a standard plaque or film. The second stage is normally the better predictor of customer use.
Lock the let-down recipe
- Carrier and base-resin grades, including lot controls.
- Masterbatch concentration and weighing resolution.
- Drying, blending and mixing procedure.
- Machine, screw configuration, temperatures, speed and residence time.
- Purge sequence and contamination controls.
- Specimen thickness, surface, cooling and conditioning time.
Measure color development, not only Delta E
Report the agreed total color difference, but also inspect Delta L*, Delta a* and Delta b* to understand whether the lot is lighter/darker, redder/greener or yellower/bluer. Compare spectral curves when two formulations have similar Lab values but may behave differently under another illuminant. Where tint strength matters, define a separate strength calculation or controlled dilution series instead of treating Delta E as a complete formulation diagnosis.
Control opacity and surface
A translucent or low-pigment plaque can be influenced strongly by its backing. Use specified black, white or same-color backing, or make the plaque optically opaque. Hold thickness and mould surface constant. If the production part is textured, establish whether the approval plaque or the replicated production texture is the release surface.
Instrument fit
A benchtop system such as the SD-800B or SD-900B is a strong candidate for controlled plaque, pellet and transmission workflows. The SD-500 can support portable plaque and production checks. Validate the chosen aperture and mode on the actual specimen.
See pellet measurement, moulded-part control and supplier/manufacturer color QC.
Last reviewed 21/09/2026 · Level: Intermediate
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