With the growing demand for environmentally friendly coatings and inks, water-based aluminium paste has become an important metallic pigment in modern coating systems. Compared with traditional solvent-based metallic pigments, water-based aluminium paste offers lower VOC emissions and better compatibility with water-based coatings.

However, producing stable water-based aluminium paste is technically challenging because aluminium particles easily react with water and oxygen. To overcome this issue, manufacturers use different production technologies to improve stability and corrosion resistance.

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Types of Water-Based Aluminium Paste

Water-based aluminium paste is available in several visual effect grades to meet different coating requirements. Common types include:

• Fine white water-based aluminium paste

• Fine sparkle aluminium paste

• Medium sparkle aluminium paste

• Super sparkle aluminium paste

• Electroplating-resistant aluminium paste

• Aluminium pigments for water-based printing inks

In terms of pigment structure, water-based aluminium paste can also be divided into leafing aluminium paste and non-leafing aluminium paste. These structures determine how aluminium flakes orient themselves in the coating film and influence the final metallic appearance.

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Main Production Methods of Water-Based Aluminium Paste

Currently, there are three common manufacturing methods used to produce water-based aluminium paste.

1. Direct Milling Method

In this process, aluminium powder is mixed with dispersants and antioxidants. Water-soluble solvents are added, and the mixture is milled in a ball mill until the desired particle size is achieved.

Advantages

• Low production cost

• Simple manufacturing process

Disadvantages

• Safety risks during production

• Limited corrosion resistance

• Lower stability in water-based systems

Because the aluminium surface is not strongly protected, the pigment can still react with water or impurities over time.

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2. Solvent Replacement Method (Oil-to-Water Conversion)

Another method is converting traditional solvent-based aluminium paste into water-based aluminium paste. This process uses high-boiling water-soluble solvents such as butyl glycol ether to replace the original mineral oil through distillation.

During the process, dispersants and antioxidants are added to improve stability.

Advantages

• Better metallic appearance

• Brighter aluminium effect

Disadvantages

• Limited corrosion resistance

• Stability may still be insufficient in certain water-based systems

• Compatibility varies depending on coating formulations

This method mainly relies on physical adsorption of polymers on the aluminium surface to reduce water contact.

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3. Nano-Silica Surface Coating Technology

The most advanced method involves depositing nano-sized silicon dioxide (SiO₂) particles onto the aluminium surface through chemical reactions.

During this process, a protective layer of silica forms around the aluminium flakes. The coating thickness is typically 50–100 nanometers, creating a dense barrier that prevents corrosion from water, oxygen, acids, and alkaline substances.

The silica particles used in this process are usually 10–30 nanometers in diameter. When the reaction is precisely controlled, the particles become more uniform, forming a smoother and stronger protective layer.

Advantages

• Excellent corrosion resistance

• High stability in water-based coatings

• Improved chemical resistance

Disadvantages

• Higher production cost

• Requires chemical reaction equipment such as reactors

• Additional processing steps, including oil removal and surface treatment

Despite the higher cost, this method provides the most reliable performance for demanding coating applications.

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Why Surface Protection Is Important for Water-Based Aluminium Pigments

Aluminium particles are naturally reactive when exposed to water. Without proper surface protection, the aluminium flakes can oxidize, leading to gas formation, coating defects, or reduced metallic appearance.

For this reason, modern water-based aluminium pigments increasingly rely on advanced surface coating technologies to improve long-term stability and compatibility with water-based coating systems.

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Applications of Water-Based Aluminium Paste

Water-based aluminium paste is widely used in environmentally friendly coatings and printing systems, including:

• Water-based industrial coatings

• Decorative paints

• Printing inks

• Packaging coatings

• Plastic coatings

As environmental regulations continue to become stricter worldwide, water-based metallic pigments are expected to play an increasingly important role in the coatings industry.