Printing

Effect pigments in printing applications serve a different set of constraints than coatings or plastics. Film thickness in gravure and flexo printing is measured in microns — typically 2–8 µm per layer — which means only fine-particle pigment grades are physically compatible with the process. A 60 µm pearlescent platelet cannot pass through a gravure cell designed to meter a 5 µm ink film. Particle size selection in printing is therefore the first and most constraining technical decision, preceding all other formulation considerations. All Kolortek products referenced for printing applications are fine-particle grades selected from within each series — not full-range offerings.

The printing industry is under simultaneous pressure from two directions: sustainability and differentiation. On the sustainability side, solvent-based gravure and flexo inks are facing increasing VOC regulation in the EU and North America, driving reformulation toward water-based and UV-cure systems — which have different pigment compatibility requirements than traditional solvent-based ink vehicles. On the differentiation side, brand owners and packaging designers are demanding visual effects that standard CMYK process printing cannot reproduce — metallic lusters, color-shift effects, holographic finishes, and thermochromic inks — to create shelf impact and anti-counterfeiting functionality that conventional printing cannot deliver.

Security printing represents a separate and distinct segment within the broader printing industry. Banknotes, negotiable securities, identity documents, and pharmaceutical packaging require overt and covert anti-counterfeiting features that are difficult to reproduce with standard printing equipment. Optical variable pigments (OVPs), holographic pigments, color-shift inks, and thermochromic systems are established components of security ink formulations — and sourcing consistency and batch documentation are as important as optical performance in this segment.

Kolortek Solutions for Printing

Technical Formulation Guidance

Particle Size and Process Selection The starting point for any effect ink formulation is confirming the maximum allowable particle size for the intended print process. For gravure printing, fine grades below 15 µm are typically required — in practice, grades with a D97 below the gravure cell depth of the target cylinder. For flexo printing with standard anilox volumes, grades below 20–25 µm are generally workable, but this must be confirmed against the specific anilox specification. Screen printing is the most flexible process for effect pigments, accommodating grades up to 60–80 µm depending on mesh count — a 120 mesh screen can accommodate larger particles than a 200 mesh screen. Before formulating, confirm the particle size distribution of the specific Kolortek grade against the process parameters.

Loading Levels and Dispersion Effect pigment loading in printing inks is typically lower than in coatings — 2–8% by weight in the final ink is a common starting range for pearlescent effects in gravure and flexo, with screen printing inks running higher at 5–15% depending on the desired intensity and pigment type. Higher loading increases the pearl effect up to a point, after which crowding of platelets reduces rather than increases luster. Dispersion should use low-shear agitation — a paddle or anchor mixer — to incorporate the pigment without fracturing platelets. The pigment should be added to the ink vehicle after the base resin and solvent system is prepared, not during high-speed milling stages. For UV-cure ink systems, the photoinitiator system should be selected for compatibility with the pigment's surface chemistry — some surface-treated grades interact with specific photoinitiators and should be evaluated before adoption.

Vehicle and Substrate Compatibility Mica-based pearlescent pigments are generally compatible with nitrocellulose, polyamide, polyurethane, and acrylic resin systems used in gravure and flexo inks, as well as water-based acrylic and styrene-maleic anhydride vehicles. UV-cure acrylate systems are also compatible. For water-based ink systems, the pigment's dispersibility in aqueous media should be confirmed — some grades may require a wetting agent or surface treatment for stable dispersion in water-based vehicles. Holographic and aluminum-based pigments require additional compatibility evaluation in water-based systems, as the aluminum layer in holographic pigments can react with strongly acidic or alkaline ink vehicles. Adhesion on the target substrate — particularly plastic films — should always be evaluated independently of pigment selection, as the ink vehicle rather than the pigment is the primary adhesion determinant.

Application Examples

Example 1: Premium Cosmetic Packaging — Gravure Pearl Ink A specialty ink manufacturer develops a pearl gravure ink for printing on cosmetic folding cartons. KT 100 Silver White fine grade (D97 < 12 µm) is dispersed at 5% in a nitrocellulose-polyurethane gravure vehicle at 25–30 seconds viscosity (Din Cup 4). The ink is applied at 3–4 µm dry film thickness on a coated GD2 board substrate. Pearl luster is visible on the finished carton under standard retail lighting, producing a visible effect within the printed design without requiring a separate hot-stamp or laminate foil application. Batch-to-batch color matching is managed by specifying the pigment's particle size distribution (D50 and D97) alongside the standard ink color specification.

Example 2: Security Label — Thermochromic and Color-Shift Elements A security label printer develops a tax stamp with two overt anti-counterfeiting elements: a thermochromic ink element that changes from red to colorless when touched (body temperature activation), and a screen-printed color-shift element using Chromashift pigment that shows different colors at 0° and 45° viewing angles. The thermochromic ink is formulated in a water-based screen printing vehicle at 8% pigment loading with the activation temperature confirmed from the grade-specific TDS. The Chromashift element is formulated separately in a clear UV-cure screen printing varnish at 10–12% loading, applied as a spot-printed register element over the base label design.

Example 3: Promotional Merchandise — Holographic Screen Print A promotional print shop develops a holographic effect screen print for a premium branded merchandise range. KT Holographic Pigments fine grade is formulated at 12% in a plastisol screen printing base for textile printing, and at 10% in a water-based acrylic medium for paper and card stock printing. The holographic rainbow diffraction effect is most visible when the ink is applied over a black or dark substrate — the print specification includes a dark underbase recommendation. Mesh count is selected at 86 mesh (34 lines/cm) to accommodate the holographic flake particle size without screen blockage.

Why Choose Kolortek for Printing

Manufacturing Experience and Grade Consistency Kolortek has manufactured effect pigments for over 20 years. For printing ink applications specifically, batch-to-batch particle size consistency is a critical quality parameter — a shift in D97 between batches can cause the grade to become incompatible with a gravure cylinder or anilox roll that performed correctly with the previous batch. Kolortek's manufacturing process controls are focused on particle size distribution consistency as a primary quality output, not just color appearance.

Fine-Grade Availability Across the Full Effect Range Most effect pigment manufacturers offer fine grades in standard pearl categories but have limited or no fine-grade options in specialty effects — holographic, thermochromic, color-shift, and fluorescent grades are often available only in coarser particle sizes. Kolortek's printing-oriented product selection covers fine grades across all major effect categories, allowing ink formulators to access the full range of effect types within the particle size constraints of gravure and fine-mesh screen printing.

Technical Documentation and Support Particle size distribution data (D10, D50, D97), TDS, SDS, and CAS numbers are available for all printing grades. For customers developing inks for food contact packaging applications, Kolortek's technical team can provide chemical composition data to support the ink manufacturer's compliance assessment process. Application development support — including formulation starting points and dispersion guidance for specific ink vehicle systems — is available upon request.

Contact Kolortek

If you are developing printing inks that require metallic, pearlescent, or specialty visual effects, Kolortek can help you identify suitable pigment grades for your formulation.

Contact our team to request:

• Product samples for printing ink evaluation

• Technical data sheets and pigment specifications

• Application guidance for printing processes

Our technical team can assist with pigment selection based on your ink system, printing method, and desired visual effect.