PIGMENT YELLOW 42/ IRON OXIDE YELLOW 313
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Technical Information
What Is PY42 / IRON OXIDE YELLOW 313
PY42 / Iron Oxide Yellow 313 is a synthetic iron oxide pigment (FeOOH) with CAS number 51274-00-1 and Colour Index 77492. It possesses a goethite crystal structure and serves as a permanent yellow pigment widely used in industrial applications. This grade provides excellent weather resistance and lightfastness, making it far more durable outdoors than organic yellow pigments, though its tinting strength is lower. It dehydrates to red iron oxide (Fe₂O₃) above approximately 180°C, a critical thermal limitation for plastic processing. Synthetic production ensures higher purity and consistency compared to natural ochres.
Why Choose IRON OXIDE YELLOW 313
This specific grade is optimized for coatings and plastics applications, offering outstanding durability and color retention under outdoor conditions where organic yellows would fade or degrade. For coatings, it provides excellent opacity, chemical resistance, and weatherability, making it ideal for industrial and architectural paints. In plastics, its thermal stability up to 180°C allows safe processing in most thermoplastics, provided temperature limits are respected. Compared to natural iron oxide yellows, this synthetic grade delivers superior color consistency, higher purity, and fewer impurities. Since there are no sibling grades available, this formulation represents a targeted performance profile for demanding exterior and high-durability applications.
Key Features
- Goethite crystal structure provides exceptional lightfastness and UV resistance for prolonged outdoor exposure.
- Synthetic production ensures high purity, consistent particle size, and batch-to-batch color reproducibility.
- Excellent weather resistance and chemical durability outperform organic yellow pigments in exterior applications.
- Thermal stability up to approximately 180°C, beyond which it dehydrates to red iron oxide, limiting use in high-temperature plastics.
- Lower tinting strength than organic yellows but offers superior opacity and long-term color retention in coatings and plastics.
C.I.NO.: PY42
Advantage:
Main Application Recommended: Coatings, Plastics
Product Description – PY42
IRON OXIDE YELLOW 313 (PIGMENT YELLOW 42) offers excellent light and weather fastness, ensuring long-lasting color stability in outdoor applications. It also features good chemical resistance and low cost, making it a cost-effective choice for coatings, plastics, and construction materials.
Recommended Application
wall bricks, cements, paving bricks, paintings, coatings, plastics, rubber and so on
Technical Data
| Product Information | ||||
| Chemical Type | CAS NO. | 51274-00-1 | ||
| C. I. Name | Pigment Yellow 42 | EINECS / ELINCS NO. | 257-098-5 | |
| C. I. Constitution No. | 77492 | Chemical Formula | ||
| Technical Performance | ||||
| Full Shade | Tint | |||
| Weather Resistance | 5 | 5 | Heat Stability °C | 200°C |
| Light Fastness | 8 | 8 | ||
| Physical Properties | ||||
| Physical Form | Powder | Moisture： | ≤1.0% | |
| Content（α-FeOOH）： | ≥86.0% | PH Value: | 3-7 | |
| Oil Absorption: | 25-35 ml/100g | Density： | 0.4-0.6g/cm3 | |
| Residue on Sieve(90 sieve)： | ≤0.3% | particle shape： | Needle type | |
| Water soluble content： | ≤0.3% | Color strength: | 95%~105% | |
| Chromatic aberration △E: | ≤1.0 | |||
| Packaging | ||||
| 25kgs/bag 1000kgs/Pallet | ||||
| Storage | Shelf Life | 5 years | ||
| Should be stored in cool, dry and ventilate place. | ||||
| TRANSPORTATION | ||||
| Avoid inversion, sunlight, moisture and crash. Avoid damage the package. | ||||
- Light fastness: Light fastness rating is assessed on 1 to 8 Blue Wool scale where 1 = ‘Poor’ and 8 = ‘Excellent’.
- Heat Stability : Heat stability values given indicate the maximum temperature at which the pigment can be stoved for 10 min. on the full shade and in reductions without undergoing any significant change in shade.
- Oil absorption: The oil absorption is determined on the basis of EN ISO 787-5 and given in g linseed oil per 100 gm. pigment.
- Solvent bleeding: The bleeding in solvents is tested using the powder grades and the visual rating given on 1 to 5 Grey scale
where 1 = ‘Heavy bleeding’ and 5 = ‘No bleeding”
Technical Note — The data and recommendations provided are based on HONOR Pigment’s internal testing and manufacturing experience. They are offered in good faith to assist customers in evaluating product suitability for their specific applications. As processing conditions, formulations, and end-use requirements vary widely, customers should conduct their own validation under actual use conditions. HONOR Pigment makes no warranties, express or implied, regarding the accuracy of this information or its fitness for any particular purpose. Nothing herein shall be construed as a license or recommendation to infringe any patent. HONOR Pigment’s standard terms and conditions of sale apply.oduct contains particles < 0.1 μm. Any user of this product is responsible for determining the suitability of Honor Pigments’s products for its particular application & to ensure that any proprietary rights & existing laws & legislation are observed.
Why Choose Honor Pigments?
- 🌍 Global Export Expertise — Trusted by customers in 40+ countries for consistent quality and reliable supply
- ✅ Strict Quality Control — ISO 9001 certified with batch-to-batch consistency and zero-defect policy
- 💰 OEM Production Advantage — Competitive pricing without compromising pigment performance
- 🧪 Technical Support — Free color matching, formulation advice and sample testing before bulk order
Frequently Asked Questions About PY42
What specific coating and plastic applications is Iron Oxide Yellow 313 best suited for?
Iron Oxide Yellow 313 (PY42) is ideal for industrial coatings, architectural paints, wood stains, and powder coatings where heat stability up to 180°C is sufficient. In plastics, it excels in polyolefins (PE, PP), rigid and flexible PVC, and engineering plastics like ABS and nylon processed below 200°C. Its chemical resistance makes it suitable for coil coatings, automotive primers, and exterior masonry paints. However, it is not recommended for high-temperature engineering plastics (e.g., PBT, PEEK) or masterbatches requiring long melt residence above 200°C, as partial dehydration can shift the shade toward red and reduce opacity. Always conduct a short-term thermal hold test with your resin system to confirm compatibility.
What are the key performance limitations regarding lightfastness and weather resistance?
PY42 offers excellent lightfastness (7–8 on the Blue Wool scale) and very good weatherability for interior and moderate exterior use. However, it loses gloss and can chalk in prolonged direct sunlight, especially in high-bake, low-film-thickness applications. Unlike calcined iron oxides, the hydrated structure of 313 breaks down under continuous UV and moisture cycles. For outdoor coatings exposed to severe conditions (e.g., Florida or Arizona weathering), a topcoat or stabilizing additives (UV absorbers, HALS) are recommended. In plastics, 1,000-hour QUV tests often show acceptable ΔE below 2.0, but the pigment should not be relied upon for 5-year-plus uncoated exterior exposure. This pigment is best suited for shaded façade paints, interior design coatings, and industrial equipment where direct sunlight is limited.
How does Iron Oxide Yellow 313 compare to other yellow iron oxides like 920 or 42?
PY42 (C.I. 77492) is a synthetic hydrated iron oxide, distinct from dehydrated grades (e.g., Yellow 920, which is a calcined, more reddish-brown oxide). Compared to synthetic Yellow 42 (montmorillonite-based hybrid), 313 offers stronger tinting strength, better opacity, and more vibrant greenish-yellow undertone. However, 313 has higher oil absorption (~40–50 g/100g) versus 920 (~30–35 g/100g), meaning it can alter viscosity in high-load formulations. It is more heat-stable than organic yellows like PY83 but less chroma-saturated. For plastics, 313 provides superior cost-effectiveness and weatherability over organic yellows, but cannot match the lightfastness of bismuth vanadate (PY184) in high-end outdoor applications. Choose 313 when you need a bright, clean yellow with excellent hiding power at a moderate cost per kilo.
What processing parameters must be controlled during compounding and dispersion?
Critical parameters: 1) Processing temperature must stay below 200°C (preferably 180°C max) to avoid dehydration, which turns the pigment brownish-red and reduces opacity. 2) High-shear dispersion is recommended to break agglomerates—use a two-roll mill for PVC or a twin-screw extruder with a dispersion screw for masterbatch. 3) Due to its high specific gravity (~4.1 g/cm³), prewetting with a wetting agent (e.g., polymeric dispersant at 2–5% on pigment weight) prevents settling in liquid coatings. 4) pH of the paint system should remain between 5 and 9; strongly acidic or alkaline conditions can leach iron ions, causing yellow staining or catalytic degradation of the binder. For plastics, do not exceed 3–5 minutes residence time at 190°C in injection molding. A short melt filtration test (e.g., 100-mesh screen) will reveal any undispersed pigment specks.
What are the best storage practices and viable substitution options if PY42 is unavailable?
Store Iron Oxide Yellow 313 in a cool, dry environment (below 40°C, relative humidity <60%). It absorbs moisture up to 1.5% w/w, so bags must be kept sealed; moisture ingress can cause clumping and poor dispersion. Shelf life is typically 5 years when stored properly—no chemical degradation occurs, but free-flow may diminish. If substitution becomes necessary, consider: 1) Synthetic Yellow 42 (e.g., Lanxess Bayferrox 42) for near-identical shade and chemistry but slightly duller hue; 2) Yellow Iron Oxide 920 for higher heat stability (250°C) but redder shade; 3) Organic PY83 (e.g., Cromophtal Yellow 83) for brighter chroma but lower hiding power and higher cost; 4) For non-food contact applications, PY184 (bismuth vanadate) can replace PY42 with superior weatherability but at 3–5x the price. Always adjust letdown ratios to match color intensity—PY42 is typically used at 2–8% in plastics and 10–20% in paints by total pigment weight.
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