Glossary of colour and pigment terms

Afterglow: Light emitted by a phosphorescent pigment after the light source is removed.
Binder: The film-forming polymer that holds pigment in an ink, coating or textile print.
Bleed: Migration of a colorant from a coloured material into a neighbouring material or liquid.
Carrier: The polymer or liquid in which a pigment is pre-dispersed, such as the polyethylene in a masterbatch.
Certificate of analysis (CoA): Document giving the test results of a delivered batch against agreed limits.
CIELAB: A colour space describing colour by lightness (L*) and two colour axes (a*, b*), used for instrumental colour control.
CLP: The EU Regulation on Classification, Labelling and Packaging of substances and mixtures, based on GHS.
Colour Index (C.I.): International reference system that gives each colorant a generic name and number, such as Pigment Blue 15:3.
Colour strength: The colouring power of a pigment or dispersion relative to a standard, usually expressed in percent.
ΔE (delta E): A single number expressing the difference between two colours; smaller is closer. ΔE00 is the modern formula.
Dispersion: A stable mixture of fine solid particles distributed in a liquid or polymer.
Dosing / let-down ratio: The amount of concentrate added to the final material, as a percentage or a ratio such as 1:50.
Dye: A colorant that dissolves in the medium it colours.
Efflorescence: White salt deposits on the surface of concrete or masonry.
Filler masterbatch: Concentrate of mineral filler such as calcium carbonate in a polymer carrier.
Flocculation: Re-agglomeration of dispersed pigment particles, which reduces colour strength and gloss.
GHS: The UN Globally Harmonized System for classifying and labelling chemicals.
HALS: Hindered amine light stabilisers that protect polymers from UV degradation.
Hiding power / opacity: The ability of a coloured layer to cover what lies beneath.
Interference pigment: An effect pigment whose colour comes from light interference in thin layers.
IR-reflective pigment: A pigment that reflects near-infrared sunlight, reducing heat build-up.
Leafing: Behaviour of treated metal flakes that float to the surface of a wet film.
Light fastness: Resistance of a colour to fading under light, often rated on the blue wool scale from 1 to 8.
Masterbatch: A concentrated mixture of pigments and/or additives in a carrier polymer, added to plastics during processing.
Melt flow rate (MFR): The mass of polymer extruded through a standard die in ten minutes, a measure of flow (ISO 1133).
Migration: Movement of a substance out of a material, for example from packaging into food.
Oligomer: A short-chain polymer; in UV curing, the backbone resin that sets the main film properties.
Pearlescent pigment: A platelet effect pigment giving lustre through interference.
Photoinitiator: A compound that absorbs UV light and starts the curing of UV inks and coatings.
Pigment: A colorant that is insoluble in the medium it colours and is dispersed as particles.
PTC ink: Positive temperature coefficient ink whose resistance rises with temperature, used in self-limiting heaters.
REACH: The EU Regulation on Registration, Evaluation, Authorisation and Restriction of Chemicals.
Regulatory summary sheet (RSS): A Flychem document summarising inventory status, restricted-substance screening and market positioning.
Safety data sheet (SDS): A 16-section document describing the hazards of a product and how to handle it safely.
Shade standard: The approved physical or numerical colour reference that each batch is compared with.
SVHC: Substance of very high concern on the REACH candidate list.
Thermochromic pigment: A pigment that changes colour with temperature.
Transparent oxide: Very fine iron-oxide pigment that appears transparent while keeping iron-oxide durability.
Universal masterbatch: Masterbatch with a carrier designed to suit several polymer types.
Viscosity: Resistance of a liquid to flow.