What Is Chemical Resistance in Pigments? Performance Against Acids, Alkalis and Solvents

Chemical resistance in pigments refers to their ability to maintain their color and essential properties when exposed to chemical substances during manufacturing or their intended application. It is an important technical consideration in pigment selection, particularly in industrial paints, plastics, coatings, textiles and chemical product manufacturing.

Providing the desired color is not the only requirement. A suitable pigment should also withstand exposure to acids, alkalis, solvents and other chemical compounds without experiencing undesirable color changes, dissolution or chemical degradation.

Why Is Chemical Resistance Important in Pigments?

A pigment with insufficient chemical resistance may cause the finished product to change color or lose its visual properties over time. In some cases, the pigment's chemical structure may be affected, while in others the surrounding resin, binder or carrier system may be damaged.

For this reason, pigment selection should consider both the chemical resistance of the pigment itself and the resistance of the complete formulation in which it is used.

Chemical resistance is particularly important in the following applications:

• Industrial paints: Coatings exposed to acids, alkalis and chemical cleaning agents.
• Plastic manufacturing: Plastic components, packaging and technical products that come into contact with chemicals.
• Epoxy and resin systems: Protective surfaces and floor coatings used in chemically demanding environments.
• Automotive industry: Components exposed to fuels, oils, cleaning chemicals and environmental influences.
• Textile applications: Fabrics subjected to washing, bleaching and other chemical processes.

1. Acid Resistance of Pigments

Acid resistance describes how well a pigment maintains its chemical structure and color properties when exposed to acidic environments. The type of acid, its concentration, temperature and contact duration can all influence pigment performance.

Some pigments remain highly stable in acidic conditions, while others may react chemically, change color or lose certain structural properties.

Acid resistance should be carefully evaluated when selecting pigments for industrial coatings, chemical storage tank paints, protective surfaces and plastic products that may come into contact with acidic substances.

Factors Affecting Acid Resistance

• The chemical structure and composition of the pigment
• The type and concentration of the acid
• Contact duration and environmental temperature
• The binder or resin system in which the pigment is used
• Manufacturing and application conditions

2. Alkali Resistance of Pigments

Alkali resistance refers to a pigment's ability to maintain its color and structural stability when exposed to basic chemical substances. Cement, concrete, plaster, detergents and certain industrial cleaning products are examples of applications that may create alkaline environments.

The behavior of pigments under high-pH conditions is particularly important in construction chemicals and mineral-based coatings. Pigments that are unsuitable for alkaline environments may experience color changes or performance loss over time.

When selecting pigments for concrete, mortar and cement-based products, manufacturers should consider not only color strength but also stability under highly alkaline conditions.

3. Solvent Resistance of Pigments

Solvent resistance describes how a pigment behaves when exposed to organic solvents, including its resistance to dissolution, color bleeding, chemical changes and other undesirable effects.

It is important to distinguish pigments from soluble colorants. Pigments are generally insoluble colorants, but certain pigment types may partially dissolve in specific solvents or exhibit color bleeding under particular conditions. This behavior depends on the pigment's chemical structure.

When selecting pigments for solvent-based paints and coatings, manufacturers should evaluate the solvent type, resin system and overall formulation together.

Applications Where Solvent Resistance Matters

• Solvent-based industrial paints
• Automotive paints and coating systems
• Epoxy and polyester resin applications
• Plastic and polymer-based products
• Protective coatings requiring chemical resistance

For more information about colorants used in solvent-based applications, explore our Solvent Dyes category.

Chemical Resistance of Organic and Inorganic Pigments

Organic and inorganic pigments can exhibit different resistance properties when exposed to acids, alkalis and solvents due to their chemical structures. However, whether a pigment is organic or inorganic is not enough to determine its overall chemical resistance. Performance depends on its specific chemical composition, manufacturing process, purity and intended formulation.

Chemical Resistance of Organic Pigments

Organic pigments are widely used in plastics, paints, printing inks and coating applications because of their high color strength, bright shades and extensive color range.

Their chemical resistance varies considerably depending on their molecular structures. Some organic pigments offer good stability in acidic and alkaline environments, while others may be more sensitive to specific chemicals.

In solvent-based systems, solvent resistance and the tendency to dissolve or bleed into the surrounding medium should be carefully evaluated. Pigment dispersion and pigment solubility are two different properties and should not be confused.

Common applications of organic pigments include:

• Plastic and masterbatch manufacturing
• Industrial and decorative paints
• Printing inks
• Automotive and general coating systems
• Textile coloring applications

Explore our Organic Pigments category for different color options and technical properties.

Chemical Resistance of Inorganic Pigments

Inorganic pigments are colorants based on mineral compounds or metal-containing chemical structures. Many inorganic pigments offer good stability under demanding conditions, including exposure to heat, light and certain chemicals.

They are commonly used in construction materials, industrial paints, protective coatings and plastic manufacturing, where reliable performance is required.

However, not all inorganic pigments have the same resistance to acids, alkalis and solvents. For example, some metal oxide pigments provide excellent chemical stability, while certain mineral-based or metal salt pigments may be affected by specific acidic or alkaline environments.

Common applications of inorganic pigments include:

• Concrete, cement and construction chemicals
• Industrial paints and coatings
• Plastics and technical polymer products
• Ceramics and construction materials
• Manufacturing processes involving high temperatures

Discover our range of Inorganic Pigments for industrial coloring applications.

How Is the Chemical Resistance of Pigments Tested?

The chemical resistance of pigments is evaluated by exposing samples to selected chemical substances under controlled conditions. The purpose is to identify color changes, structural deterioration, dissolution or bleeding tendencies.

1. Acid Resistance Testing

The pigment is exposed to an acidic solution with a defined concentration for a specified period. After exposure, the sample is examined for color changes, dissolution, surface alterations and, where necessary, changes in chemical composition.

Results may vary depending on the acid type, concentration, temperature and exposure duration.

2. Alkali Resistance Testing

In this method, the pigment is evaluated in an alkaline environment with a defined pH level. This test is particularly relevant for pigments intended for cement- and concrete-based applications, where high alkalinity can affect color stability.

After testing, the sample is examined to determine whether the pigment has maintained its color and chemical stability.

3. Solvent Resistance Testing

This method evaluates how a pigment interacts with specific solvents. Depending on the solvent, possible effects include partial dissolution, color bleeding or changes in appearance.

For pigments used in paint and coating manufacturing, compatibility with the solvent and resin system should be assessed together.

4. Color Change and Visual Inspection

Samples taken before and after chemical exposure are compared. Color differences can be measured using a spectrophotometer and evaluated through the ΔE value. Surface appearance, sedimentation, color bleeding and visible structural changes may also be examined.

What Should Be Considered During Chemical Resistance Testing?

Reliable evaluation requires standardized test conditions. Comparing results obtained under different conditions may lead to misleading conclusions.

• The type and concentration of the chemical should be clearly specified.
• Exposure time and temperature should be controlled.
• The pigment quantity and sample preparation method should remain consistent.
• It should be stated whether the pigment is tested individually or within a finished formulation.
• Color changes and physical observations should be evaluated together.

One important point is that the chemical resistance of a pigment alone does not guarantee the chemical resistance of the finished product. Binders, resins, additives and manufacturing conditions can also influence final performance.

How to Choose the Right Pigment Based on Chemical Resistance

When selecting pigments for applications that require chemical resistance, the decision should not be based solely on color and cost. The chemicals the pigment may encounter, operating temperature, exposure duration and manufacturing process should all be considered.

Choosing an unsuitable pigment can lead to color changes, surface defects, bleeding and reduced product performance. Defining the technical requirements of the application is therefore an essential step in pigment selection.

1. Identify the Chemical Environment

The first step is to determine which chemicals the pigment will encounter. Acidic, alkaline and solvent-based environments may require different resistance properties.

• Acidic environments: Consider the acid type, concentration and exposure duration.
• Alkaline environments: Evaluate high-pH conditions, particularly in concrete, cement and construction chemical applications.
• Solvent-based systems: Examine the solvent type and the pigment's potential for dissolution or color bleeding.

2. Review the Pigment's Technical Properties

Technical Data Sheets (TDS) are important reference documents when selecting pigments. Relevant properties may include chemical resistance, heat resistance, lightfastness, color strength and recommended applications.

It is also important to understand the test conditions behind the reported resistance values. Different manufacturers may use different testing methods and evaluation criteria, so results should not automatically be considered equivalent.

3. Consider the Resin and Binder System

The chemical resistance of a pigment is not the same as the chemical resistance of the paint or coating system in which it is used. Even if a pigment is chemically stable, damage to the binder system can negatively affect the performance of the finished product.

For this reason, pigment compatibility should be evaluated when working with epoxy, polyester, polyurethane and other resin systems.

4. Test Under Actual Production Conditions

Laboratory results provide valuable information, but pigment performance should also be evaluated under actual manufacturing conditions.

Producing test samples allows manufacturers to examine pigment behavior within the formulation, color stability and appearance after chemical exposure. For demanding applications, small-scale trials before full production can help identify potential problems.

Chemical Resistance Requirements Across Different Industries

The level of chemical resistance required from a pigment varies according to the application and operating environment.

Plastic and Masterbatch Manufacturing

In plastic manufacturing, pigments must be compatible with the polymer matrix and additives used during processing. For plastic products exposed to chemicals, color stability and potential pigment migration should also be evaluated.

Selecting suitable pigment grades is particularly important for cleaning product packaging, technical plastic components and polymer products exposed to chemicals.

Explore our Organic Pigments, Inorganic Pigments and Plastic Additives for plastic manufacturing applications.

Industrial Paints and Coatings

In industrial paints, pigments may be used in coating systems exposed to acids, alkalis, solvents, oils and other chemicals.

In these applications, the chemical resistance of the resin, hardener and other formulation components is just as important as pigment performance. The durability of the finished coating depends on the compatibility of the entire system.

Epoxy and Polyester Applications

In epoxy and polyester systems, pigments should be compatible with the resin, disperse uniformly and remain stable throughout the curing process. For chemical-resistant floor coatings and protective surfaces, pigment selection should reflect the intended operating conditions of the finished product.

Construction Chemicals and Concrete

Pigments used in concrete, mortar and cement-based products should be suitable for highly alkaline environments. Moisture, outdoor exposure and variations in application conditions should also be considered.

Common Mistakes When Selecting Chemically Resistant Pigments

Several technical mistakes during pigment selection can lead to quality problems after manufacturing.

• Selecting pigments based only on color: A pigment that looks suitable may not provide sufficient resistance in the intended chemical environment.
• Using organic or inorganic classification as the only criterion: Chemical resistance depends primarily on the specific chemical structure of each pigment.
• Confusing solvent resistance with solubility: Pigment dispersion behavior and dissolution in a solvent are different properties.
• Ignoring test conditions: Comparisons can be misleading if concentration, temperature and exposure duration are not specified.
• Skipping finished-product testing: The performance of a pigment on its own does not guarantee the resistance of the final formulation.

Choosing the Right Pigment with Tüver Pigment

Selecting the right pigment for chemically demanding manufacturing processes is important for maintaining product quality and long-term performance. Clearly defining the application environment and production requirements helps identify suitable pigment options.

At Tüver Pigment, we supply pigment and colorant solutions for plastics, paints, coatings and various industrial applications. We consider application requirements, desired color properties and technical specifications when evaluating suitable product options.

Explore our product range or contact our team for further information about pigment solutions for your application.

Frequently Asked Questions

Which pigments have the highest chemical resistance?

No single pigment group can be considered the most resistant in every chemical environment. Some inorganic pigments offer excellent chemical stability, while certain organic pigments also perform well under specific acid, alkali and solvent conditions. Selection should be based on the chemicals involved in the application.

Are organic pigments resistant to acids?

Some organic pigments provide good resistance in specific acidic environments, while others may be affected depending on the acid type and concentration. Product-specific technical data and appropriate testing are necessary.

Are inorganic pigments resistant to alkalis?

Many inorganic pigments perform well in alkaline environments, but their resistance varies by pigment type. Pigments intended for concrete and cement applications should be evaluated under high-pH conditions.

Do pigments dissolve in solvents?

Pigments are generally insoluble colorants. However, some may partially dissolve or exhibit color bleeding in particular solvents. Their behavior depends on the pigment's chemical structure and the properties of the solvent.

How can the chemical resistance of a pigment be determined?

The manufacturer's Technical Data Sheet should be reviewed, including the test conditions used to establish resistance values. For critical applications, the pigment should also be tested within the actual formulation.

Conclusion

The resistance of pigments to acids, alkalis and solvents is an important technical consideration in industrial manufacturing. Selecting the right pigment requires evaluating the chemical environment, pigment structure, resin system and production conditions together.

Choosing a pigment suitable for the intended application and conducting appropriate tests before production can help reduce quality issues and achieve more consistent product performance.