Colored Masterbatch & Color Matching: Frequently Asked Questions

Workflow: customer provides a color number or sample → spectrophotometer measures Lab values → a heat- and weather-compatible pigment combination is selected → lab extruder trial → standard plaque issued → on-machine verification and fine-tuning. Professional matching must weigh pigment heat resistance (processing temperature), migration resistance (application) and weatherability (indoor/outdoor) — it is not just mixing colors.

Yes. Provide a Pantone number (e.g. PANTONE 485C) or RAL number and the colorist works to the corresponding color-card Lab values. Note that color cards are printed/coated colors; the same number in plastic is affected by resin base color, gloss and transparency — final approval is always against a plastic standard plaque.

Industry practice: ΔE≤1.0 is excellent for appearance parts, ΔE≤1.5 acceptable for general appearance parts, ΔE≤2.0 for structural parts. What matters more is batch-to-batch stability: after first-article approval, compare every batch against the standard plaque. We normally deliver appearance-part masterbatch at ΔE≤1.0–1.5.

Four cause categories: pigment batch variation (same chemistry, different makers), carrier base-color fluctuation, color-shade shifts from processing temperature and shear differences, and dosing/mixing variation. Countermeasures: lock pigment suppliers and formulation, retain standard samples for comparison, and fix process parameter windows.

Check four metrics: TiO2 content (50%+ recommended for appearance parts), TiO2 type (rutile beats anatase in weatherability and opacity), whiteness and yellowness index, and dispersion grade (thin-wall parts need high dispersion). Outdoor parts must use rutile with a UV package; indoor low-cost parts can use medium-grade white.

Typical injection molding 1%–3%; high-opacity demands (dark regrind, high whiteness) 3%–6%; film blowing 2%–5%. It depends on white masterbatch concentration and part wall thickness: thin walls are harder to cover, so use the higher end. Determine the economical ratio by trial rather than one-size-fits-all experience.

Standard black grades run 20%–45% carbon black. For high-gloss, deep-black parts (appliance panels) use high-color carbon black at 40%–50% concentration with 1%–2% let-down; ordinary structural parts use 25%–30% concentration at 2%–3% let-down. Carbon black suffers both from poor dispersion (specks) and insufficient concentration (dull gray).

First check three things: whether the let-down is sufficient, whether the grade's carbon black concentration meets spec, and whether dispersion is complete. Remedy in order: raise let-down by 0.5 points on trial → switch to a higher-concentration grade → check mixing uniformity and back pressure. Long term, move to a higher-concentration high-color black masterbatch.

Gray is one of the hardest colors: white/black ratios are extremely sensitive to undertone shifts, and yellow-leaning TiO2 makes it look dirty. The professional approach is to use color-matching software against a Lab target, fix pigment grades, and lock the formula after the customer approves the first plaque. In production, never casually swap white or black masterbatch brands.

Fluorescent pigments have limited heat resistance (mostly 220–260°C) and will decompose and shift color on high-temperature engineering plastics; migration and lightfastness are also weaker than standard pigments, and outdoor use fades quickly. Key points: low temperature, large gates, fast shots; avoid residence; for outdoor parts switch to high-lightfastness fluorescent systems or reduce fluorescent intensity.

Pearlescent pigments are mica platelets; excessive shear destroys the layers and kills the effect. Key points: enlarge gates and runners, reduce screw speed and back pressure, avoid fine screen packs that block platelets; in blown film the oriented platelets create a pearlescent flow pattern — usable as a feature or counted as a defect.

Metallic effects rely on aligned aluminum flakes. Brightness boosters: high-gloss substrate resins, higher mold temperature, faster injection so flakes align with flow, avoiding excessive shear that breaks flakes, and polished molds. For effect parts, always trial on your own mold first to confirm the look.

Glow masterbatch contains strontium-aluminate phosphors and needs a relatively high let-down (5%–15%) for a visible afterglow; the pellets are hard, so watch screw wear. Make parts thicker (afterglow scales with thickness), use a transparent or light base color, and avoid layering with strongly opaque pigments.

Thermochromic masterbatch uses microencapsulated liquid crystals or leuco dyes that change structure — revealing or erasing color — within a set temperature range, commonly triggered at 15°C, 31°C, 44°C, etc. The microcapsules are shear-sensitive and the processing ceiling is generally 230°C; they suit low-temperature PP/PE products such as cups and bath toys.

Marble/wood grain uses "dual-masterbatch co-blending" or dedicated streaking grades: two masterbatches with distinct colors and flow are mixed at a ratio, deliberately under-mixed so the pattern streaks naturally. The key is controlling mixing time and screw shear — over-mixing gives a flat solid color, under-mixing gives harsh blotches; establish parameters by trial.

For transparent coloring use dye-based or high-clarity organic pigment masterbatch; avoid TiO2 and inorganic pigments, which turn the part cloudy. Balance heat and migration resistance; for food-contact parts confirm dye compliance with regulations. Where haze matters (caps, lamp covers), ask the supplier for transmittance data.

For outdoor parts avoid fade-prone azo reds/yellows and fluorescent shades; prefer inorganic pigment systems (titanium yellow, iron oxide red, cobalt blue) or high-grade lightfast organics (phthalocyanine blue/green, quinacridone red), paired with UV-resistant masterbatch (HALS + UV absorber) for double protection. For dark outdoor parts also watch heat absorption and warpage.

Pigments for food contact must appear on FDA 21 CFR or EU 10/2011 / GB 9685 positive lists and meet overall migration limits; vivid reds, yellows and oranges have fewer options than industrial shades, with heavy metals and aromatic amines restricted. Confirm "food-grade application" in writing when purchasing so the supplier proposes compliant pigments with reports.

It can come close: high-gloss substrate + highly dispersed black/colored masterbatch + high mold temperature and polished tool. The keys are pigment dispersion grade and carrier purity (low specks). Compared with paint-free resin it lacks mica/aluminum effect layers, but for ordinary high-gloss parts the cost advantage is clear — trial both before deciding.

Three routes: a matting masterbatch (with silica or talc types), an etched/textured mold surface, or switching to a matte-grade resin. Matting masterbatch is flexible but raises melt viscosity and cuts impact — use cautiously on thin-wall parts. For demanding appearance parts, in-mold texturing is the most stable option.

Streaks usually stem from large melt-speed differences between masterbatch and substrate, uneven plasticization, or poor pigment dispersion. Countermeasures: switch to a high-flow grade on the same carrier family, raise screen mesh to force dispersion, increase melt temperature and back pressure moderately, and keep let-down below the limit. For films use film-blowing-specific grades, not injection grades.

At weld lines, converging pigment fronts show as color shifts. Mitigation: raise melt and mold temperature for better front fusion, improve venting, relocate gates, and choose a well-dispersed lower-concentration grade (high-concentration grades concentrate locally and show lines more). Evaluate weld-line positions together with the color scheme at the design stage for appearance parts.

Migration is pigment or additive moving from inside the part to the surface, showing as staining, fogging or color rubbing off. Causes include small pigment molecules, poor resin compatibility, or plasticizer presence. Countermeasures: choose high-molecular-weight pigments, use dedicated carrier grades, add anti-migration agents in soft PVC and similar systems, and verify by trial.

Four main causes: insufficient light/weather fastness (no lightfast system for outdoor use), insufficient heat resistance (color already shifted during processing), oxidation (missing antioxidant package), and migration. First distinguish "off-color out of the machine" from "fades in use": heat issues point to temperature, in-service fading points to weatherability and UV protection.

Common methods: press the part against white PVC or a light plaque under heat and pressure and inspect staining, or run migration tests to GB/T cyclic standards. For outdoor and household parts add lightfastness (xenon arc) and heat-aging tests. Demand the data from suppliers — don't judge by looks alone.

The two materials in a two-shot part must be compatible with matched shrinkage, with masterbatch fed into each barrel separately. A typical combination is rigid ABS + soft TPE overmolding, with a TPE-specific grade for the soft component. Note the second material's processing temperature must not burn the already-colored first shot — choose heat resistance for the higher temperature on both sides.

Transparent masterbatch is designed for low haze (dye systems); at a normal 1%–2% let-down the effect on transmittance is minimal. But mistakenly using a grade containing TiO2 or high filler will fog the part immediately. For haze-sensitive products (lamp covers, bottles) use dye-based grades and require haze data from the supplier.

When deep shades (bright red, navy, black) lack coverage over light or regrind bases: raise let-down, switch to a higher-concentration grade, or prime the base first (gray/white masterbatch to neutralize the base) before applying the color. The most economical fix is often shifting the base color toward the target rather than endlessly deepening the top color.

Sequence: purge with a high-melt-index general purging compound (or regrind) first; dark-to-light benefits from a small dose of white masterbatch to push color out; light-to-dark transitions directly; black/white swaps waste the most material, so schedule them apart in production planning. Dedicated machines for high-value transparent parts avoid purge losses.

Standard colors take 1–2 rounds: the first round produces 2–3 close formulations, and after fine-tuning the second round seals the standard. Effect colors (metallic, pearlescent, fluorescent) and strict-match key accounts may need 2–4 rounds. Providing a physical sample is far faster than a color number alone — it sharply raises first-round hit rate.