Which Water-based Pigment Dispersion are suited for exterior wall coatings requiring bright and long-lasting colors?

Which Water-based Pigment Dispersion are suited for exterior wall coatings requiring bright and long-lasting colors?

To formulate vivid and durable colors for exterior wall coatings, the selection of water-based pigment paste should be guided by the following criteria:

1. Weather Resistance and Light fastness

Vividness depends on the choice of pigment, whereas durability is determined by the pigment's molecular structure.

- Light fastness: Measures the ability to retain color under UV radiation; it is recommended to select colorants with a light fastness rating of 7–8.

- Weather Resistance: Measures color retention under comprehensive climatic conditions (sunlight, humidity, temperature fluctuations); it is recommended to select colorants with a weather resistance rating of 4–5.

2. Pigment Dispersion type

For different color families, priority should be given to colorants containing the following high-performance pigment components:

1). Red/Yellow pigment paste Series (Areas Prone to Fading)

- Organic Types: Traditional Benzidine Yellows or Permanent Reds are highly susceptible to fading under intense sunlight. It is recommended to use colorants based on DPP Red (Pigment Red 254), Anthraquinone Red, or Pigment Yellow 110/139. These are high-performance organic pigment colorants that offer vivid colors and excellent weather resistance, though they come at a higher cost.

Wonderchem is one of chinese pigment dispersion suppliers, we supply  top grade of pigment dispersion, which have excellent Heat resistance and light resistance etc. the water based pigment dispersion are widely used into PTFE emulsion , exterior wall coating etc.

- Inorganic Types: If maximum long-term durability is the priority, Iron Oxide Red, Iron Oxide Yellow, or Bismuth Vanadate Yellow (Pigment Yellow 184) colorants are the preferred choices. While their vividness is slightly lower than that of organic types, they offer lower costs and superior light fastness and weather resistance.

 

2). Blue/Green  pigment paste Series

- Phthalocyanine Types: Phthalocyanine Blue (BGS) and Phthalocyanine Green colorants are the top choices for exterior walls. Not only do they offer vivid colors, but their stable molecular structures also ensure excellent weather resistance and light fastness. Alternatively, inorganic Ultramarine Blue or Chrome Green pigment paste may be selected; while they possess good weather resistance and light fastness, their tinting strength is relatively low, and their vividness is less pronounced.

 

3). Black/White pigment paste Series

- Carbon Black pigment paste: For exterior wall applications, black colorants should be formulated using high-structure, high-weather-resistance carbon black pigments. - Titanium White Colorant: For white pigment paste, it is essential to select a product formulated using rutile-type (R-type) titanium dioxide.

 

4). Other Vivid Color Series

Primarily based on inorganic pigment color paste, supplemented by high-weather-resistance organic pigments for color correction (a composite formulation). Depending on specific coloring requirements—and by comprehensively balancing color vividness against color durability—a combination of inorganic and organic pigment paste can be blended to create a wide range of other color series. During the tinting process, it is also crucial to maintain a balance in the pigment volume concentration; generally, the addition level of the colorant paste should not exceed 10% of the total formulation volume to avoid compromising the stability of the coating system.

 

3. "Alkali Resistance"—A Mandatory Consideration

Exterior wall substrates typically consist of cement mortar or concrete, which are strongly alkaline in nature. If the water based pigment paste possesses poor alkali resistance, the color will rapidly turn gray, fade to white, or develop unsightly mottling.

Verification: When purchasing, it is imperative to confirm that the pigment paste possesses an alkali resistance rating of Grade 4–5.

 

4. System Compatibility and Fineness

- Impact on Film Formation: Exterior wall paints typically utilize pure acrylic or silicone-acrylic emulsions. The pigment paste must not contain an excessive amount of surfactants; otherwise, this will compromise the water resistance of the coating film, potentially leading to whitening or "blooming" of the paint film after exposure to rain.

- Fineness: It is recommended to select high-quality colorant pastes with a fineness (particle size) of less than 5μm. This ensures not only strong tinting strength but also uniform pigment dispersion, thereby minimizing the risk of color floating or mottling within the coating.

Wonderchem is one of chinese pigment dispersion suppliers, we supply  top grade of pigment dispersion, which have excellent Heat resistance and light resistance etc. the water based pigment dispersion are widely used into PTFE emulsion , exterior wall coating etc.