Zinc white CAS No. 1314-13-2

Product Description

Zinc white is a white pigment primarily composed of zinc oxide (ZnO) that has been utilized in various fields such as art, cosmetics, and industry since the 19th century. It was developed as a safer alternative to toxic lead white and is known for its pure white color with a slightly cool undertone. Zinc white is semi-transparent to semi-opaque and has excellent lightfastness, making it resistant to fading under UV light. It is non-toxic, which is advantageous for use in cosmetics and pharmaceuticals. However, it can react with acids and may darken when exposed to hydrogen sulfide. In artistic applications, zinc white is valued for its ability to create subtle highlights and glazes, especially in oil paints. It dries slowly but forms a flexible film. Despite its benefits, zinc white can be less opaque than titanium white and may crack in thick applications. Its reactivity with free carboxylic acids in oil binding media can lead to the formation of zinc soaps, which can cause protrusions and mechanical failure in paintings. This was observed in Salvador Dalí's "Couple with Clouds in their Heads," where zinc white-containing oil paint degraded due to exposure to high temperatures and acid gases. Zinc white remains a versatile pigment with a wide range of uses, from fine art to industrial applications.

Product Use & Characteristics

Properties

• Chemical Formula: ZnO (zinc oxide)
• Molecular Weight: 81.4 g/mol
• Color: Pure white with a slightly cool, bluish undertone
• Opacity: Semi-transparent to semi-opaque, depending on the formulation
• Tinting Strength: Moderate, lower than titanium white
• Drying Time: Slower than other white pigments, advantageous for techniques requiring longer working time
• Yellowing Resistance: Highly resistant to yellowing when mixed with oil
• Brittleness: Tends to create a brittle paint film over time, leading to cracking and delamination in thick layers
• Toxicity: Non-toxic, safe for use in cosmetics and pharmaceuticals
• Lightfastness: Excellent, resistant to fading under UV light
• Reactivity: Alkali-resistant but reacts with acids; can darken when exposed to hydrogen sulfide

Synthesis Methods

• Indirect Method: Also known as the French method, it uses metallic zinc as the raw material. This method produces submicron prismoidal particles with higher purity.
• Direct Method: Also known as the American method, it involves heating zinc ores and a reducing agent to reduce zinc compounds to zinc before oxidation. This method produces larger acicular particles.
• Wet Chemical Process: Used for producing ZnO for applications in textiles and rubber industries.

Uses

• Artistic Paints:
  • Oil Paints: Used for glazing and subtle highlights due to its transparency. Forms a flexible film but can be brittle if used alone in thick layers.
  • Watercolors: Known as "Chinese white," it is popular for its clean, bright tone and ability to create subtle tints.
  • Acrylics: Used for delicate highlights and areas requiring luminosity.
• Cosmetics & Sunscreens:
  • UV Protection: Provides broad-spectrum UV protection.
  • Pharmaceuticals: Used in powders, foundations, and ointments due to its mild antiseptic properties.
• Industrial Applications:
  • Rubber Manufacturing: Acts as a vulcanization accelerator.
  • Ceramics: Used in various ceramic applications.
  • Coatings: Used in house paints, mastics, and other coatings.
  • Catalyst: Acts as a catalyst in chemical reactions.

Advantages

• Non-toxic: Safe for skin contact and use in cosmetics and pharmaceuticals.
• Lightfastness: Excellent resistance to fading under UV light.
• Glazing and Layering: Ideal for glazing and layering in paintings due to its transparency.
• Mixing White: Excellent for lightening colors without making them opaque or chalky.

Disadvantages

• Lower Covering Power: Less opaque than titanium white, requiring more pigment to achieve the same effect.
• Brittleness: Can create a brittle paint film, leading to cracking and delamination in thick applications.
• Formation of Zinc Soaps: Reacts with free carboxylic acids in oil binding media to form zinc soaps, which can cause protrusions and mechanical failure.

Historical Context

• Development: Developed in the 18th–19th centuries as a safer alternative to toxic lead white.
• Popularity: Popular among Impressionist and Post-Impressionist painters for its clean, bright tone.
• Commercial Name: Originally marketed as "Chinese white" in watercolors.
• Degradation Issues: Known for causing degradation issues like chalking and metal soaps in paintings.

Other Information

• Degradation in Artworks: Zinc white-containing oil paints can degrade, forming zinc soaps, zinc formate dihydrate, zinc acetate dihydrate, and zinc sulfide. This can lead to ring formations and a matt, white-looking semi-transparent material on the surface, as observed in Salvador Dalí's "Couple with Clouds in their Heads."
• Modern Use: Still used today, though often replaced by titanium white in many applications due to its higher opacity and better mechanical properties.

Why us!

Qingdao Sigma Chemical Co., Ltd., established in January 2017 and headquartered in Qingdao, China, is a reliable chemical supplier. Specializing in pharmaceuticals, biochemical intermediates, and research chemicals, the company offers a diverse product portfolio, including peptides (e.g., Tirzepatide, Semaglutide), nootropics, veterinary products, and APIs, often marketed with ≥99% purity and COA certification. We provides R&D, custom synthesis, and contract manufacturing services at various scales, while claiming a global export presence across 100+ countries. With international warehouses in the USA, Europe, Australia, and Canada, Qingdao Sigma Chemical also facilitates drop-shipping and reshipments, positioning itself as a key supplier for laboratory and research applications.