HP Blue 4693 — Pigment Blue 27 (Prussian Blue / Iron Blue) for Offset Inks & Industrial Coatings | Honor Pigments

Technical Information

What Is PB27

Pigment Blue 27 (CAS 14038-43-8, CI 77510) is iron hexacyanoferrate — Prussian Blue, the first modern synthetic pigment, discovered in Berlin around 1704 and still commercially significant three centuries later for the deep midnight-blue shade space that no other pigment chemistry occupies at a comparable cost. Its crystal structure, Fe₄[Fe(CN)₆]₃ · xH₂O, is a cubic framework of iron ions bridged by cyanide ligands in a mixed-valence Fe(II)-CN-Fe(III) network whose intense blue color arises from intervalence charge transfer — electron hopping between iron oxidation states — rather than the π-π* transitions that color organic pigments like copper phthalocyanine. This inorganic chromophore delivers very high tinting strength at low cost, a dark navy-blue mass-tone that copper phthalocyanine cannot produce without blending, and sufficient lightfastness for indoor and limited-exterior applications. Its defining chemical vulnerability is alkali sensitivity: under alkaline conditions, the iron-cyanide framework hydrolyzes, destroying the blue chromophore and releasing free cyanide species — a limitation that defines where and how PB27 can be used.

Why Choose HP BLUE 4693

HP BLUE 4693 is a high-performance Prussian Blue engineered for publication gravure printing inks and industrial coating systems where the deep, dark navy-blue shade of PB27 delivers a color-space value that copper phthalocyanine blue — in any crystal modification or surface treatment — cannot replicate. PB15, in every grade from PB15:0 through PB15:4, produces a clean, bright blue with either green or red undertones. It cannot produce the dense, almost-black midnight blue that PB27 achieves at practical pigment loadings. In publication gravure, this shade distinction matters most in four-color process printing, where PB27 deepens the shadow tones of process black and produces the rich dark-blue solids that editorial and advertising layouts demand — a contribution that no PB15 grade can make without unacceptably high pigment loading that disrupts ink rheology and printability. In industrial coatings, PB27 produces the dark navy and midnight-blue finishes specified for machinery, tooling, and industrial equipment where the coating must communicate durability and professionalism through a deep, serious blue rather than a bright decorative one. HP BLUE 4693 maximizes the PB27 value proposition: its controlled particle size and surface treatment optimize tinting-strength development while managing the alkali-sensitivity limitation through particle engineering that reduces the reactive surface area exposed to alkaline components in ink vehicles, coating resins, and substrates. For formulators who know the difference between a bright process cyan and a deep midnight navy — and whose application demands the latter — HP BLUE 4693 is the Prussian Blue grade engineered for reliable, consistent performance in the printing and coating systems where PB27’s unique shade position earns its place.

Key Features

• Deep midnight-blue mass-tone unmatched by copper phthalocyanine. The iron-cyanide intervalence charge-transfer chromophore produces a dark, dense navy blue that PB15 cannot reach without blending in carbon black or violet pigments that compromise color cleanliness and add formulation complexity — PB27 delivers this shade space from a single pigment chemistry.
• Very high tinting strength at economical pigment loading. Prussian Blue’s intrinsic tinting strength, among the highest of all blue pigments, means formulators achieve target color density with less pigment than PB15 alternatives require in deep-blue applications, reducing raw-material cost and minimizing the pigment-volume-concentration impact on ink and coating film properties.
• Controlled particle size for optimized dispersion and shade development. The particle size distribution is engineered for rapid wet-out and full color-strength development in the hydrocarbon and ester-based vehicle systems typical of publication gravure inks and alkyd-based industrial coatings, eliminating the extended grind cycles that damage PB27’s crystal integrity.
• Reduced alkali sensitivity through particle engineering. While all Prussian Blue grades are fundamentally alkali-sensitive at the chemical level, HP BLUE 4693’s controlled particle morphology minimizes exposed reactive surface area, extending the pigment’s practical processing window in ink and coating formulations that contain mildly alkaline components from resin systems, substrate treatments, or process-water carryover.
• Consistent batch-to-batch shade for process-color reliability. Tight manufacturing control over the iron-cyanide precipitation and oxidation conditions that determine PB27’s crystal size, hydration state, and cation composition delivers the shade consistency that publication gravure and industrial coating formulators require for long-run color fidelity in process and spot-color applications.

Recommended Applications

Primary — Publication Gravure Printing Inks. Magazines, catalogs, direct mail, and editorial supplements where PB27’s deep navy-blue shade deepens the shadow tones in four-color process printing and produces rich dark-blue solids that PB15 process cyan cannot achieve at commercially viable pigment loadings. HP BLUE 4693 is engineered for the hydrocarbon and ester solvent systems that dominate publication gravure, with particle size control optimized for the engraved-cylinder transfer and thin-film drying conditions of high-speed rotogravure presses.

Secondary — Industrial Coatings & Offset Process-Black Enhancement. Industrial alkyd and air-dry coatings for machinery, equipment, tooling, and metal furniture where the specification calls for dark navy or midnight-blue finishes that communicate durability and professional-grade quality. Solvent-based packaging gravure inks where deep shadow-tone enhancement adds visual impact to premium-brand graphics. Offset printing inks for publication and commercial work where PB27 is blended into process black to neutralize brownish undertones and produce colder, more neutral shadow tones. Artist and educational-grade colorants where Prussian Blue’s historical significance and unique shade remain valued.

Shade Selection Guide. For bright, clean green-shade or red-shade blue in any ink, coating, or plastics application, the PB15 family — HP BLUE 4558 (solvent gravure), HP BLUE 4559 (solvent flexo), HP BLUE 4394 (offset), HP BLUE 4453 (UV-curable), and others — delivers the color space that copper phthalocyanine dominates. For premium exterior durability, HP BLUE 4689 (PB15:4 chlorinated) provides maximum weatherfastness. HP BLUE 4693 earns its position when the specified shade is deep midnight or navy blue — a color space that PB15 cannot reach without blending — and when the application environment is controlled for pH, as in publication gravure inks, industrial solvent-borne coatings, and offset process-black shading. PB27 is not a replacement for PB15; it is a complementary chemistry that extends the blue palette into darkness levels that copper phthalocyanine, for all its versatility, was never designed to occupy.

Technical Data

Rating Scale Notes

Fastness values reported on a 1–5 scale (5 = best) unless noted otherwise. Lightfastness measured in full shade per ISO 105-B02. Heat stability tested at the indicated temperature for 10 minutes in the specified medium. PB27 is an inorganic pigment with moderate lightfastness — adequate for indoor and limited-exterior applications but not equivalent to PB15 copper phthalocyanine in long-term outdoor exposure. Alkali resistance is the defining chemical limitation: PB27 decomposes irreversibly under alkaline conditions (pH > 7–8). All ratings represent typical values; performance may vary with formulation, substrate, and processing conditions. Prospective users should validate in their own system before commercial adoption.

Packaging

HP BLUE 4693 is supplied in 25 kg multi-wall paper bags with an inner polyethylene liner, palletized and stretch-wrapped for export-standard protection. Alternative packaging configurations — including 10 kg bags, 500 kg flexible intermediate bulk containers (FIBC / big bags), and custom packaging — are available on request. All packaging carries lot-number traceability back to the production batch record.

Storage

Store in a cool, dry, well-ventilated area away from direct sunlight, moisture, and sources of ignition. Recommended storage temperature: 5–35 °C. Keep containers tightly sealed when not in use. Avoid stacking pallets beyond the manufacturer’s recommended tier height to prevent bag damage. In high-humidity environments, condition the product to ambient temperature before opening sealed packaging to prevent condensation on the pigment surface. Prussian Blue is hygroscopic; moisture ingress can alter shade and dispersibility.

Shelf Life

36 months from the date of manufacture when stored unopened in original packaging under the recommended storage conditions. Beyond the stated shelf life, the product may still be usable; re-test critical application properties (color strength, dispersion behavior, moisture content) before use. Opened packaging should be consumed promptly or re-sealed with desiccant protection. Prolonged exposure to high humidity or temperature cycling may accelerate changes in moisture content and dispersibility even within the nominal shelf-life window.

Transportation

HP BLUE 4693 is not classified as a dangerous good under UN, DOT, IMDG, or IATA transport regulations. No special handling or placarding is required for road, sea, or air freight. As with all fine-powder pigments — inorganic or organic — avoid generating airborne dust during loading and unloading; standard industrial hygiene practices apply. The product should be secured against moisture ingress and physical damage during transit. For international shipments, consult the latest SDS and local regulatory guidance to ensure compliance with destination-country chemical inventory registration requirements.

Frequently Asked Questions About PB27

Prussian Blue versus phthalocyanine blue — which pigment for dark navy printing inks?

Prussian Blue (PB27, CI 77510, CAS 14038-43-8) and copper phthalocyanine blue (PB15, CI 74160, CAS 147-14-8) occupy fundamentally different shade positions. PB15 produces bright, clean blues — green-shade in β-form, red-shade in α-form — that excel at process cyan and decorative applications where brilliance and transparency are the visual objectives. PB27 produces dark, dense midnight-to-navy blues with a depth and richness that PB15 cannot achieve without blending in carbon black, which muddies the shade and kills the chroma. In publication gravure, PB27 serves a dual role: it deepens the shadow end of the process-black channel, reducing brownish undertones, and it delivers rich dark-blue solids that editorial layouts demand. HP BLUE 4693 is the PB27 grade purpose-built for this specific color-space value — it is not competing with PB15 for process cyan, but complementing it for the deep end of the blue spectrum that phthalocyanine was never designed to cover.

PB27 alkali sensitivity — what formulators need to know before using Prussian Blue

Prussian Blue’s alkali sensitivity is its defining chemical constraint: exposure to pH above approximately 7–8 hydrolyzes the iron-cyanide framework, bleaching the blue color and potentially releasing cyanide species. This is not a surface-treatment problem that can be fully engineered away — it is a thermodynamic property of the Fe(II)-CN-Fe(III) bond network that constitutes the chromophore itself. Practical consequences for formulators: PB27 cannot be used in water-based coatings with alkaline pH buffers, in emulsion paints stabilized with alkaline thickeners, or on alkaline substrates like fresh concrete or plaster without a sealing primer. HP BLUE 4693 (CI 77510, CAS 14038-43-8) mitigates this inherent vulnerability through particle engineering that reduces reactive surface area, buying the formulator a wider pH processing window — but it remains a Prussian Blue, and its application envelope is defined by pH control. The reward for operating within that envelope is the deep midnight-blue shade that no alkali-stable alternative delivers at a comparable cost.

PB27 heat stability limits — processing temperature guidance for ink and coating applications

Prussian Blue’s heat stability ceiling — typically 140–180°C depending on the specific grade, hydration state, and cation composition — is substantially lower than copper phthalocyanine’s 300°C-plus capability. This is an intrinsic property of the iron-cyanide crystal: thermal energy drives off coordinated water molecules and can trigger partial decomposition of the cyanide framework, producing a greenish or brownish discoloration rather than the characteristic deep blue. In practical terms, PB27 is fully stable through publication gravure drying, air-dry alkyd coating cure, and offset ink oxidative drying — all of which operate well below the thermal decomposition threshold. It is not suitable for powder coating cure cycles, high-bake industrial enamels above 150°C, or plastics processing. HP BLUE 4693 (CI 77510, CAS 14038-43-8) is optimized for the lower-temperature processing window where PB27 delivers its unique shade value: publication gravure, conventional offset, and air-dry industrial coatings — applications where the thermal demand never tests the pigment’s ceiling and the deep navy blue earns its formulation cost advantage.

Prussian Blue in four-color process printing — enhancing shadow tone depth

In standard four-color process printing — CMYK — the black channel (K) alone often produces shadow tones with a perceptible brownish or warm cast, particularly in publication gravure on uncoated or lightly coated paper stocks where the black ink’s carbon-black pigment interacts with the paper’s natural yellow-brown undertone. Adding a small proportion of PB27 to the process black formulation neutralizes this warmth by introducing a cold blue component that shifts the perceived shadow color toward neutral gray or cool black without the green cast that PB15 would introduce at equivalent loading. HP BLUE 4693 (CI 77510, CAS 14038-43-8) is the PB27 grade engineered for this process-black shading application in publication gravure: its high tinting strength means a small addition produces a large color shift, keeping the pigment loading low enough that ink rheology and printability remain unaffected while the shadow tones gain the cold neutrality that high-end editorial and advertising reproduction demands.

CI 77510 versus CI 74160 — selecting the right blue pigment for industrial coatings

CI 77510 (Pigment Blue 27, Prussian Blue, CAS 14038-43-8) and CI 74160 (Pigment Blue 15, copper phthalocyanine, CAS 147-14-8) serve complementary rather than competing roles in industrial coatings. PB15 is the choice for bright, clean blues with excellent all-round fastness — the universal blue pigment that covers the majority of industrial coating shade requirements from light sky blue to full-strength process cyan. PB27 is the choice when the specification calls for dark navy or midnight blue — the deep end of the blue spectrum where PB15 runs out of darkness at commercially practical pigment loadings, and where adding carbon black would kill the chroma that distinguishes a rich navy from a dull dark gray. HP BLUE 4693 earns its place in the formulator’s toolkit for this specific dark-blue segment: it is not a PB15 replacement but a PB15 complement, extending the achievable blue palette into the deep end that phthalocyanine chemistry cannot reach alone, in the pH-controlled solvent-borne coating systems where PB27’s alkali sensitivity is fully managed.

Disclaimer

The information provided herein is based on our current knowledge and experience and is accurate to the best of our understanding. It does not constitute a legally binding warranty of specific product properties or suitability for a particular application. Users are responsible for conducting their own tests to determine the suitability of HP BLUE 4693 for their specific purposes and for compliance with applicable laws and regulations. Nothing herein shall be construed as a recommendation to use any product in conflict with any third-party intellectual property rights. PB27 Prussian Blue is an inorganic pigment containing iron and cyanide components; consult the Safety Data Sheet (SDS) for complete handling, storage, and disposal guidance before use.