What is a masterbatch in injection moulding?

Masterbatch is concentrated pigment in a carrier resin, added to uncoloured base resin. A typical addition is 2–5% of total blend mass; use the supplier-specified dosage and compatible carrier for the resin and colour.

What colour tolerance can injection moulding hold?

A well-controlled process holds a Delta E of about 1.0–2.0 against an agreed master plaque; ΔE 1.0 is roughly the smallest difference a trained eye reliably sees. Tighter than ΔE 1.0 is possible on stable materials with pre-coloured compound, but it must be agreed in writing with the measurement method, illuminant and geometry stated.

Can you match a Pantone or RAL colour in plastic?

Approximately, yes — exactly, no. Pantone references are ink on paper and RAL references are paint films; plastic colour depends on resin, wall thickness, gloss and texture, so a direct transfer is impossible. The professional route is a masterbatch matched to a physical plastic plaque approved by both parties, with the Pantone or RAL reference as the starting target.

Why does the same colour look different in different plastics?

Because the pigment is only part of the colour. The natural base shade of the resin tints everything — ABS is yellowish, PC is water-clear, PP is milky-translucent — and opacity, wall thickness and surface finish all change how light returns from the part. A masterbatch matched in one resin must be re-matched for another.

Is masterbatch or pre-coloured compound cheaper?

Masterbatch usually wins at small to medium volumes: it costs roughly €4–15/kg but is dosed at 2–5%, adding only €0.10–0.50 to each kilogram of material. Pre-coloured compound adds €0.30–1.00/kg across the whole quantity and carries minimum orders of 25 kg to 1 tonne, but gives the tightest colour consistency — it wins for critical colours and large single-colour volumes.

Does regrind affect part colour?

Yes. Regrind carries extra heat history, which yellows most polymers, and any colour contamination in the scrap stream tints the blend. Cosmetic parts therefore run low regrind ratios or none at all, and colour-critical parts should have the maximum regrind content written into the specification.

Colour Matching and Masterbatch in Injection Moulding: A Guide

"Match our brand colour" is one of the most common — and most poorly specified — requests in injection moulding. Colour in plastic is created by pigments, modified by the resin, shifted by the process and judged by the human eye under variable lighting; a Pantone number alone survives none of those steps. This guide explains how moulded colour is actually made, what tolerances are honest, and how to write a colour specification that production can hold.

Four ways to colour a moulded part

Method	Cost impact	Consistency	Minimum order	Best for
Masterbatch dosed at machine	+€0.10–0.50/kg material	Good (ΔE 1.5–2.0 typical)	25 kg masterbatch	Most coloured parts, multiple colours
Pre-coloured compound	+€0.30–1.00/kg across all material	Best (ΔE 1.0–1.5)	25 kg–1 t per colour	Critical colours, large single-colour runs
Liquid colour	Similar to masterbatch	Good, needs dosing equipment	Small	Very high-load colours, some thermosets
Dry pigment	Cheapest	Poorest; dispersion risk	Small	Non-cosmetic industrial parts

Masterbatch is the default for good reason: one natural resin stock serves every colour, carrier-matched grades disperse cleanly at a 2–5% let-down, and colour changes need only a purge. Pre-coloured compound earns its premium when the colour is safety- or brand-critical and the volume justifies dedicated material.

Why RAL and Pantone are starting points, not tolerances

A Pantone reference defines ink on coated paper; a RAL reference defines a paint film. Neither defines a polymer, a wall thickness, a gloss level or a viewing geometry — and all four move perceived colour. A 2 mm wall in translucent PP cannot show the same colour as a 4 mm wall in opaque ABS, whatever the pigment. This is why professional colour matching ends in a physical artefact: a moulded master plaque, signed by both parties, that becomes the colour. The Pantone or RAL code is the brief; the plaque is the contract.

Delta E: the honest tolerance

Instrumental colour measurement expresses difference as Delta E (ΔE) in CIELAB space — a single number combining lightness, hue and chroma differences. Practical benchmarks:

ΔE ≤ 1.0: barely visible to a trained eye; achievable with pre-coloured compound and stable process control
ΔE 1.0–2.0: the normal commercial band for masterbatch-coloured parts
ΔE > 2.0–3.0: visible to most observers; acceptable only on non-cosmetic parts

A ΔE number is meaningless without its method: the same part reads differently under different instruments. The specification must state the colour space (CIELAB), illuminant (D65 is the daylight standard), observer angle (10°), measurement geometry (d/8° sphere, specular component included, is common for plastics) and where on the part to measure.

Metamerism: why approved colours disagree in the shop

Two samples can match under one light and mismatch under another — metamerism — because they reflect different spectra that happen to look equal under the approval light. The classic trap: a colour approved under office fluorescent light shifts visibly in daylight or under retail LED. Defences are pigment selection (a match built on similar pigment chemistry to the reference is less metameric) and multi-illuminant approval: check the master plaque under D65 daylight, store lighting and at least one LED source before signing it. Optical brighteners in white or light parts add their own twist, fluorescing under UV-rich light.

What shifts colour during moulding?

Even with a fixed masterbatch, the process moves colour:

Natural resin base shade — ABS starts yellowish, PC water-clear, PP milky; the same pigment loads read differently in each, so colours are matched per resin, not once per brand palette
Melt temperature and residence time — hot, slow processing degrades pigment and polymer alike, darkening or yellowing the part
Shear — small gates and high injection speeds can shear-sensitive pigments and shift shade
Regrind content — extra heat history yellows the base; cosmetic parts cap regrind at low ratios, as the regrind rules guide explains
Wall thickness and surface — thicker walls and matte textures read darker and duller; a colour approved on a gloss plaque will not match a textured part, a link to the surface finishes guide
Glass fibre and flame retardants — both mute and grey the base colour, limiting how bright a filled grade can go

How to specify colour so production can hold it

Approve physical master plaques in the actual resin, thickness and surface finish — two signed sets, one for each party
State the instrumental tolerance: ΔE limit, CIELAB, D65/10°, d/8° geometry, measurement location
Approve under multiple light sources to catch metamerism before production does
Fix the material variables: resin grade, masterbatch type and ratio, maximum regrind content
Agree batch retention samples so disputes compare artefacts, not memories

Where moulded-in colour cannot reach — exact multi-colour graphics, metallic effects, soft-touch finishes — the answer is a secondary process, covered in the decorating guide.

Related guides

Have a brand colour that must survive production? Send Nordmould your colour reference and drawings — Agree the colour reference, approval plaque, acceptance limits and matching costs in the project quotation.