Pigment Orange 5 (CAS 3468-63-1): A Practical Buyer's Guide to This Industrial Workhorse

If you’ve ever wondered what gives certain printed packages that punchy reddish-orange color without fading after six months on a shelf — chances are, Pigment Orange 5 is involved. It’s not the newest colorant on the market; it’s actually been around for decades. But in the world of industrial pigments, longevity tends to mean one thing: the stuff actually works.

This guide covers everything a coatings formulator, ink technician, or procurement manager typically needs to know about Pigment Orange 5 — from its chemistry and performance specs to where it fits (and where it doesn’t) in real-world applications. We’ll also address some common sourcing questions, since most of the world’s supply now comes from China.

What Exactly Is Pigment Orange 5?

Pigment Orange 5 belongs to the monoazo class of organic pigments. Its Colour Index designation is C.I. 12075, and you’ll sometimes see it sold under trade names such as Permanent Orange RN, Fast Orange RN, or Hansa Orange. The IUPAC name is 1-[(2,4-dinitrophenyl)azo]-2-naphthol, and its CAS registry number is 3468-63-1.

The molecule is relatively compact — molecular formula C₁₆H₁₀N₄O₅, MW 338.27 — which is part of why it performs well at modest use-levels. It’s synthesized through a standard diazotization-coupling sequence: 2,4-dinitroaniline is diazotized in hydrochloric acid with sodium nitrite, then coupled with 2-naphthol in alkaline media. The resulting precipitate is a bright reddish-orange powder with a melting point around 302–318°C (literature value: 306°C).

Table 1. Chemical Identity Summary

Property	Value
CAS Number	3468-63-1
EINECS	222-429-4
Colour Index	C.I. 12075 (Pigment Orange 5)
Molecular Formula	C₁₆H₁₀N₄O₅
Molecular Weight	338.27 g/mol
Pigment Class	Monoazo (naphthol type)
Appearance	Bright reddish-orange powder
Melting Point	302–318°C (lit. 306°C)

Key Physical Performance Characteristics

Before reaching for any pigment in a formulation, it’s worth spending a minute on the numbers. Here’s a straightforward breakdown of what Pigment Orange 5 actually delivers:

Table 2. Physical Performance at a Glance

Characteristic	Measured Value / Grade	Notes
Particle shape	Rod-shaped crystals	Avg. diameter 0.32–0.37 µm
BET surface area	10–12 m²/g	Affects dispersibility & gloss
Oil absorption	35–50 g/100 g	Moderate — compatible with most binders
Density (bulk)	~1.48–2.00 g/cm³	Varies by particle grade
Lightfastness (ISO 105-B02)	~5–6 (Blue Wool scale)	Large-particle grade performs better
Heat resistance	Up to ~140–160°C	Check grade spec — limit varies
Transparency	Semi-transparent to opaque	Particle-size dependent
Water/alkali/acid resistance	Good	Stable in NaOH and HNO₃ solutions

A few practical things stand out here. The lightfastness rating of 5–6 is solid for architectural coatings and general-purpose inks — not quite at the level of phthalocyanine or quinacridone pigments, but perfectly adequate for applications where the substrate won’t be sitting in direct sunlight for years on end.

The heat resistance ceiling of roughly 140–160°C is worth flagging early: if your process involves high-temperature polymer extrusion (say, injection-molded engineering plastics at 250°C+), Pigment Orange 5 probably isn’t the right call. But for PVC, PE, and decorative coatings that cure at lower temperatures? It typically handles those conditions fine.

Where Pigment Orange 5 Gets Used — and Where It Doesn't

Over its long commercial history, this pigment has found a reasonably stable set of applications. Here’s an honest rundown:

3.1 Decorative and Industrial Coatings

This is probably the primary market for Pigment Orange 5. It performs well in air-drying alkyd systems, solvent-based industrial enamels, and powder coatings. In air-dry lacquers for furniture or metal surfaces, its semi-transparent character allows for interesting depth effects when layered over primers. Color strength is good — you typically need 3–8% pigment-to-binder loading to hit target opacity.

Some formulators use it to replace molybdate orange (a lead chromate-based pigment) in applications where lower regulatory burden is a priority. The color shift is noticeable — Pigment Orange 5 reads slightly redder — but for many decorative uses it’s an acceptable trade-off.

3.2 Printing Inks

Gravure and flexographic printing are two areas where this pigment is genuinely competitive. It disperses reasonably well in both solvent-based and water-based vehicles, and the relatively fine particle size supports the ink fluidity needed for high-speed presses. It’s commonly used in packaging inks, including food packaging (check applicable regulations for your market), metal foil printing, and offset lithography.

For UV-curable ink systems, you’d want to do compatibility testing first — reactivity between the nitro groups and some photoinitiators has been reported, though many formulators use it successfully with proper ink stabilization.

3.3 Plastic Coloring

Soft PVC is the sweet spot here. Pigment Orange 5 shows good compatibility with PVC plastisol systems used for cable sheathing, synthetic leather, and flexible film. It’s also used in polyethylene and polypropylene at processing temperatures within its thermal stability range. For ABS, PS, or engineering plastics that process above 180–200°C, you’re likely to see thermal degradation and color shift — most suppliers will tell you the same thing.

3.4 Artist and Specialty Colorants

You’ll find Pigment Orange 5 in higher-end acrylic and watercolor paints. The warm reddish-orange tone is valued for mixing, especially in landscape palettes. Artists appreciate that it doesn’t shift dramatically under artificial lighting — a common frustration with some cheaper orange alternatives.

Regulatory and Safety Snapshot

Pigment Orange 5 is listed in major chemical inventories: EINECS (EU), TSCA (US), AICS (Australia), DSL (Canada). The substance is generally considered of low acute toxicity in its solid powder form, though standard pigment-handling precautions apply — particulate exposure control, appropriate PPE, and avoiding skin/eye contact.

The nitro groups in the molecule mean the substance appears on some hazard communication lists, so SDS review is important before formulation decisions. Under REACH (EU), it has been registered; check the current ECHA substance page for the most up-to-date classification data before assuming compliance status for your application.

For food-contact applications, applicable regulations differ significantly by country and substrate type — this is an area where you should consult the regulatory documentation for your specific geography rather than relying on general statements.

Sourcing from China: What to Expect

China is the dominant production base for Pigment Orange 5 globally. Most suppliers are located in Jiangsu, Zhejiang, and Shandong provinces. When evaluating suppliers, a few things tend to separate reliable sources from spot-purchase vendors:

Table 3. Supplier Evaluation Checklist (China)

Criterion	What to Look For
Purity / Assay	≥96–99% by HPLC; ask for batch CoA
Particle size consistency	D50 specification and distribution data
Moisture content	Typically ≤1% for powder grades
Packaging	25 kg bags (standard) or 220 kg drums; moisture-sealed inner liner
Lead time	Spot: ~7 working days; samples: ~3 working days
MOQ	1 kg for sampling; standard min. order varies by supplier
Payment terms	T/T, L/C at sight, PayPal for small orders
Port of shipment	Shanghai or Qingdao for most bulk orders

Zhishang Bio (Zhishang Biological Co., Ltd.), based in Jinan, Shandong, is one source for this pigment. They supply it alongside a broader catalog of dyes, pigments, and pharmaceutical intermediates. Their listed MOQ is 1 kg, which is useful if you need a small quantity for formulation trials. Standard packaging runs 25 kg per bag or 220 kg drums, with shipment from Shanghai or Qingdao port. Sample orders (2–3 g, free of charge) are available to help confirm the product meets your spec before committing to a bulk purchase. You can reach their sales team at sales01@zhishangbio.com or via WhatsApp/WeChat at +8613255687161.

As with any chemical procurement, requesting a current SDS and a certificate of analysis (CoA) referencing the specific batch is standard practice. For critical formulation work, asking for particle size distribution data alongside the usual purity specifications is worthwhile.

Formulation Tips from the Field

A few practical notes that come up regularly in technical conversations about Pigment Orange 5:

Dispersion: The rod-shaped particle morphology means that bead milling typically outperforms three-roll milling for achieving full tinctorial strength. A pre-wetting step with the vehicle before milling helps prevent agglomeration.
Binder compatibility: It performs well in alkyd, nitrocellulose, acrylic, and polyurethane systems. In water-based formulations, pigment wetting agents (typically nonionic surfactants) are recommended to achieve stable dispersions.
Color matching: Because of its reddish undertone, mixing with yellow pigments gives cleaner secondary oranges than many straight yellows alone. For tinting toward yellow-orange, consider blending with Diarylide Yellow.
Shade consistency: Batch-to-batch shade variation can occur, particularly in the blue/red axis. Requesting a standardized shade sample from your supplier and doing visual comparison under D65 lighting is good practice for production-critical applications.
Outdoor durability: If outdoor weathering is a requirement, testing under actual exposure conditions is essential before finalizing the formulation — the published lightfastness ratings are guides, not guarantees, and real-world performance depends heavily on binder type, film thickness, and application environment.

How Does It Compare to Other Orange Pigments?

Pigment Orange 5 occupies a specific price-performance band. Here’s a quick comparison to its most common alternatives:

Table 4. Comparative Overview of Orange Pigments

Pigment	C.I. No.	Heat Resist.	Lightfastness	Price Range	Best For
Pigment Orange 5	12075	~160°C	5–6	Low	Decorative coatings, standard inks
Pigment Orange 13	21110	~180°C	5–6	Low–Med	Inks, rubber, plastics
Pigment Orange 34	21115	~200°C	6–7	Medium	Higher durability coatings
Pigment Orange 36	11780	~220°C	7	Medium	Automotive coatings, engineering plastics
Pigment Orange 64	12760	~240°C	7	High	High-performance industrial finishes

The takeaway: Pigment Orange 5 wins on cost and availability. If your application doesn’t require heat resistance above 160°C or lightfastness beyond grade 6, it often makes more economic sense than stepping up to the higher-performance alternatives. For outdoor-durable or high-temperature applications, PO34, PO36, or PO64 would typically be the better choice — and your formulation cost will reflect that difference.

Frequently Asked Questions

Q: What’s the difference between Pigment Orange 5 and Permanent Orange?

A: They’re often the same product marketed under different trade names. ‘Permanent Orange RN’ and ‘Fast Orange RN’ are common trade designations for C.I. Pigment Orange 5 (CAS 3468-63-1). When in doubt, verify the CAS number on the product’s certificate of analysis.

Q: Can Pigment Orange 5 be used in cosmetics?

A: This depends on jurisdiction. In the EU, not all pigment grades have cosmetic approval; you’d need to verify against Annex IV of the EU Cosmetics Regulation. In the US, the FDA regulates colorants for cosmetic use separately from industrial pigments. Don’t assume industrial-grade material is automatically suitable for cosmetic use.

Q: Is there a minimum order quantity?

A: MOQ varies by supplier. Zhishang Bio’s listed MOQ is 1 kg, which is practical for lab-scale testing. For bulk manufacturing, pricing typically improves at 25 kg, 200 kg, and metric-ton quantities.

Q: How should Pigment Orange 5 be stored?

A: Store in cool, dry conditions away from direct sunlight and moisture. Standard shelf life in sealed packaging is typically 2 years. Avoid exposure to strong oxidizing agents and concentrated acids (other than sulfuric, which dissolves it with color change).

Q: What documentation should I request when purchasing?

A: At minimum: Certificate of Analysis (CoA) referencing the batch number, Safety Data Sheet (SDS) in your required language, and — for regulated applications — declaration of compliance with relevant regulations (REACH, RoHS, etc.).

Bottom Line

Pigment Orange 5 isn’t trying to be a premium performance pigment — and that’s actually its advantage. For standard decorative coatings, conventional printing inks, PVC compounds, and art materials, it delivers consistent reddish-orange color at a cost that makes formulation economics work. The limits on heat resistance and outdoor durability are real and worth respecting, but within its appropriate use window, it remains a practical, well-understood choice.

If you’re sourcing from China and want to evaluate a sample before committing to a production order, Zhishang Bio offers small sample quantities for trial purposes.

Their contact: sales01@zhishangbio.com. WhatsApp：+86-13255687161 Web:www.zhishangbio.com

Shandong Zhishang Bio Co., Ltd

Zhishang Bio, a subsidiary of Zhishang Chemical Co., Ltd., was established in 2016 and is a new type of chemical enterprise that integrates research and development, production, and sales. Zhishang Bio always adheres to the concept of “integrity management, strict quality control, customer first”.

Through continuous efforts, significant breakthroughs have been made in industries such as pharmaceutical intermediates, pesticide intermediates, food additives, and cosmetic raw materials. The domestic trade team sells well throughout the country, while the foreign trade team is exported to more than 30 countries and regions including the United States, Russia, Spain, Brazil, and enjoys a global reputation.

Invited to participate in this exhibition, Zhishang Bio will comprehensively showcase the company’s strength and achievements in the research and development, production, and quality control of pharmaceutical and pesticide intermediates! At that time, our company will set up an CPHI exhibition at booth E12D29 at the venue, and we will take you to further understand our company’s advantageous products in detail!